How do you handle an aging Mom, and, possibly younger sister who feel (that me) moving in with Mom would be good?

Easy. Don’t do it

Don’t do it. You already know your answer. You said it yourself. You said that you did not want to move back with your mom. I suppose you want validation. Well, you have it. Follow your instincts, your heart, your gut, your logic, etc.

Just don’t move back home. Keep your home and sanity. Help mom find another solution. If your sister says that she shouldn’t be alone. Tell her to move in with her.

You have a good heart I think. You can still have a good heart living in your own home & being a loving visitor to Mum. The care 'work' does not need to be done only by you. If Mum needs more help in the future, it can be arranged. It's not bad to say no. It's looking after BOTH of you.

No to both your mother and younger sister. Don't do it. Leave her be for you have your own health issues to deal with.

Why are you considering the “opinion”(?) of your younger sister as part of your decision making?
Your sister is your sister. You are YOU.
If your mom is able to manage her life independently, then the best thing for her is doing that.
If she is UNABLE to do so, you and your sister may need to COLLABORATE to develop a care plan for her. That plan does not necessarily require EITHER ONE OF YOU to give up your present life style(s) to be Mom’s caregiver.
Do either of you hold POA for Mom in order to manage her careIf/when she does become dependent on you for help? If not, the discussion may. Red to start there.
Remind yourself often, several times a day- YOUR SISTER IS NOT ENTITLED TO MAKE OR INFLUENCE YOUR PERSONAL DECISIONS in relation to Mom’s care!

The stress would not be good for your high blood pressure. Don't do it. You deserve your own life. Follow your instincts to NOT do this!

"I fear if moving in with her happens..." You have control over what happens. Enjoy your home and belongings and let good health happen. Don't move in with your mom.

Don't you love it when other people think you should be the one. If younger sister thinks it should be you ask why not her.

Just say, sorry will not happen. It took me 40 yrs to move out and I'm staying out. Plus, would Moms facility allow you to move in? Moms OK now so let it go. But if mentioned, say sorry Mom/sister, not going to happen.

"Gee mother & sister, that just does not work for me." This is the sentence you need to memorize & to continue repeating, as necessary, until all parties understand that you are NOT moving mother in with you, nor are you moving in with mother.

40 years of living together is MORE than enough. WAY more, in fact.

If your sister thinks it's such a splendid idea for mother to live with a daughter, suggest she live with HER instead! I always advocate for being helpful, don't you? :)

Make sure to stick to your guns on this. Otherwise, you WILL lose your independence and the entire life and lifestyle you've worked so hard to build for yourself!

If mother reaches a point where she can no longer live independently, then offer to help her find a nice Assisted Living apartment.

Best of luck!

Stand in front of a mirror and practice saying, NO. It just won't work.

Keep doing it until you believe yourself. Then it will be easy to tell your mom and sister. And I agree with the others, recommend that your sister move in with your mom. Tell her you had the first 40 years, now it's her turn! Big hugs to you.

Say this over and over, NO! NO! NO! Not now! Not ever! Not in this lifetime!

After telling them that this will not work for you, expect that they won't hear it, I suggest your phrasing become, "I'm not going to do this."; The solution is not this. I will help look for other places." "Remember, moving in with me is not an option." Avoid opening the conversation up to your sis especially arguing with you about why it is indeed an option, You don't have to prove that it should not happen, You know that it is more than you can do or should do, Your sis and mom don't have to agree with you on that, Hugs to you,

When you say your "mom is in an independent facility" is that an IL type facility or is it an apartment building or retirement community apartment? If she is already in a care facility of some sort, IL with care available even I'm not sure you would even be "allowed" to take up residence there but even if you were it seems like a waste of what's being paid for already and a step backwards in the progression of things. But even if she is in an apartment and you are all seeing a need for mom to have more than visiting help in the near future this is a family discussion. Your sister and maybe even your Mom may have been batting around ideas, at least they recognize there may be a need for more hands on care, that doesn't mean they really expect you to move in and be mom's caregiver and it certainly doesn't mean you need to do it. If indeed either of them was seriously considering it maybe they were just testing the waters to see if it's something you think might work too and maybe your reaction gave mom her answer. Either way rather than staying quiet and running scared I suggest taking the bull by the horns and finding the opportunity to just ask. "It's my impression you guys have been thinking about what might come next, ideas for helping mom if something happens and she needs more care, I would like to be a part of that" and when asked or if you see it coming "I have thought about moving in with mom myself but I know I know it wont work. My arthritis will be limiting so I would need help anyway and if I give up my condo and job now I won't have anything to fall back on for my future. I know my current health issues are going to mean I require assistance sooner that I might otherwise and I don't want to put you or mom in the position of having to worry about that". or "The cost to mom will be prohibitive I think". You are right to know your limits and express them but don't let that stop you from taking part in the planning and care of your mom, just keep aware of what you can and can't do personally, your ideas and knowledge of mom can only help and is likely to be invaluable.

NO is a complete sentence. I can't even imagine living with my parents to age 40, I left the nest at 18, I couldn't wait to get on my own, to live my life on my terms not theirs.

If she is IL, then let her stay right there, soon she possibly will need AL, most facilities today have a step up program, she can then move up to AL.

It is obvious that this will not work, stand your ground and go forward with your life.

Don’t do it. Don’t do it. And tell your sister to move in and care for her and then come back to see you in 60 days. Good luck.

Your mother mentioned this idea in passing. You asked her if she was serious and she replied no, not really, she could see there would be disadvantages and difficulties.

Why would you think your sister has had anything to do with the discussion?

Meanwhile you, who would be the chief if not the only decision-maker about the whole thing, regard the idea with horror.

So... the plan isn't even in development. What on earth are you so anxious about? What do you mean, "if this happened"? - it couldn't just "happen." You would have to take an active decision to do it, and you're not going to.

I suspect the fear that's welled up in you may be related to your not having left your parents' home until you were forty, and working part-time from home perhaps not entirely through choice, and your being (quite naturally) very attached to the home you have made for yourself and the sense of security it gives you.

Did your mother perhaps think that your living together could be a way of supporting the both of you? How did the subject come up in the first place?

Don't do anything that you are uncomfortable with. That's the answer. Elder parent care is complicated enough without the children having to uproot every smidgen of the life to make sure their parents are fine. For now, I would make sure there is a Power of Attorney and all the legalities are in place, because it's just one more thing you are going to have to deal with down the road...and it can get messier if legal documents are not drawn up.

Look in the mirror and repeat after me...
"No, I am sorry but I can not do that."
then
"I'm sorry but I can not do that, you will have to find another solution, we can sit down and discuss options".

As long as this is not an option for you at any time you need to be clear now and set boundaries that you will stick to.
There is noting wrong with stating that you can not safely care for someone. This is for your safety includes mentally and financially and physically.

Why should it be you who moves in to take care of mother? Why does younger sister volunteer you for moving in with mom? Your mother may have mentioned the idea to plant the idea and feel out the possibility that you might move in with her. You don't need to do it. Heed the suggestions of others here who are reminding you to be clear about your disinterest in returning to living with your mother. Grandma 1954 states it very nicely.

Simple answer here. Absolutely, don’t do it, unless you want your life ruined.

Just be there for her; you don't have to live with her again. You have your independence after 40 years. My mom is 81 and does not want anyone living with her. And it would be very hard because she would put all her elderly ways on us and we still want to be young.

“Yeah; that ain’t gonna happen.” Just keep repeating that statement when the topic comes up. No explanations necessary. It’s YOUR life, which you’re entitled to live the way YOU want. Mom did; sister is.

Interesting to me that everyone here is saying "don't do it". I have moved back in with my Mom and have been with her for 25 years now. We have had some wonderful times and some of the hardest times of my life. Would I do it again? Yes. Would I ever advise someone else to do or not do it? No. Every single situation is so unique. My Mom spent her life helping us get our university degrees and being sure we had wonderful lives. She is sweet to a fault. She now has dementia and it is the hardest thing I've ever dealt with. I have had a kidney removed, have asthma, and other medical issues yes, but my Mom saw me through those operations and more. Caring for her has been the biggest learning time of my life. It's through challenges that we develop character and strengths arise as needed. We learn to adjust, to cry when needed, to give in ways we never thought we could. So, Louise A, follow YOUR heart and what you know about you and your Mom. Your sister doesn't know how it would work out or not, your Mom probably doesn't know, and as well-meaning as everyone here is, none of us know either. Sending you wishes that you'll make the decision that will benefit you and your Mom the most. Hugs!

No one should decide what you should do with YOUR LIFE, but YOU. Your mom is fine where she is, when she is in need of more help, then transition her to a nursing home. Being a caregiver is all consuming, don't let anyone guilt you into doing it, your gut is already telling you "no", so listen to it. Since your sister thinks it's a good idea, let her move in with mom or have mom move in with her. Not everyone has what it takes to be a caregiver. May God give you the strength and peace to say "no". You can still be helpful to your mom, but from your own home.

It sounds like every bit of this is already causing you stress, sadness, resentment, fear and dread. Why on earth would you consider this? And your mom doesn't want to live in a situation where there would be arguing. If she gets to where she cannot live alone, look into part-time care, assisted living, something that doesn't cause you to lose your hard-won independence.

It seems like your mother wasn't serious and she confirmed it with the "no."

You do Not Have to Move In, But if she Needs Care and Has aProblem being Alone, Contact a Social Worker, Adult Elderly Protrcvtive Services to Intervene.

You tell your Mom and sister......NO

All these "Don't Do It" should make you feel more confident in refusing to move in with your mom. If you were to move in in spite of not wanting to, you would resent your mother and you would feel trapped and angry.
Stay where you are and treasure having your own place and your own belongings.