Sister does not understand/respect boundaries with my family.

She no longer sees you as her sister but as the help and if you are giving attention to your visiting family she will see it as you neglecting your job of caring for her.

I can only say, regarding this, that WHENEVER WE LIVE WITH SOMEONE ELSE IT IS NOT EASY.

Think about it. Husbands and wives argue about family visits. Brothers and Sisters argue about them. Parents and children argue about them. Even roommates argue about them.

You say you "care for your sister". I don't know if she has dementia, or if she has physical needs that mean the two of you living together works for you. You have housing. She has help. So overall this works.
But clearly there was no discussion of what would work re your family visits, and what he expectations of same would be. She seems still to consider this to be HER HOME despite your being there protecting her from loss of home and independence entirely.

I can only say that there needs to be some compromise. It may be that family, if appreciable in numbers, cannot visit staying in HER home. They may need to rent a nearby motel when visiting you. And when you visit them, it's "on" for whatever you like.

Compromise, compromise. That's what living together is all about.
Stop expecting it to be perfect and for everyone to be "happy all the time". Because when you really think about it when was happy-all-the-time a thing?

You should have not given up your home. The one who should have sacrificed was your sister. If she needed help it was up to her to find options. Hire someone, sell her home so she could go to an AL. Its her who needs to make changes because of her health. You could have helped her. Now she thinks your at her beck and call. I so hope you have POA.

Boundaries and do not feel guilty about making them. You have avright to spend time with your children without your sister.

It's about setting healthy boundaries, and it sounds like you didn't do that prior to you moving in with your sister. So it's time to do that now, and let her know that occasionally you will be doing things with your children and grandchildren and that she will NOT be included, as you need that time just for you.
And make it perfectly clear that she can throw all the tantrums she wants but that isn't going to change the way things will be with you and your immediate family.
It might not hurt either to let her know that the next time she acts out or says something negative, that you're going to stay with your children until she gets her sh*t together, as you will no longer tolerate her bad behavior.
You are the one who chose to help her out so she needs to be more understanding about your need to spend time with your children and grandchildren. And if she can't it may be time to rethink your decision and start looking for a new place for you to move to, and your sister into an assisted living facility.
Since your sister has not been diagnosed with any dementia, you really can't blame any of this on that. She just may be jealous because you are out having fun with your family and she is not. That is NOT your problem or issue.
Tell her to look into different programs that Senior Services or the Shepherd Center offers, as they have a lot of fun options for seniors even with her limited mobility.
Best wishes in getting those healthy boundaries set.

Well, if she has dementia, she is never going to understand.

Maybe plan one easy thing she can do? Do your kids and grandkids visit with her when they visit you?

You could always agree with her and say something like, “yes, it would be wonderful if one day you are well enough to go on an outing with us. Let’s make a plan for that .” You know..something not passive aggressive.

I feel like sometimes they are wishing for those days and feeling the loss and not necessarily that she wants to go on an all day outing with her broken bones and incontinence. So maybe just acknowledge what she is really feeling.

just a thought

Another option try Visiting Angels or hiring someone to come in when you need time off for other things. Pay for these options should be out of her pocket not yours.
As caregivers we need to have some time off. Sister will not recognize that, we as caregivers need to tell them that.

You should also consider having your sister assessed for LTC, done by her physician. This is because in every state's Medicaid program covers LTC facility care, plus her financial qualification. You should also consult a Medicaid Planner for her home state. This way you have a care option in place for her when her condition worsens and you choose to transition her so you can have your life back.

When dementia is at play, there IS no explaining anything to them or expecting them to respect boundaries of any kind. They're incapable of it, unfortunately, and things only get worse from here. Why did you sell your home to move in with your sister?? While your heart is in the right place, you are likely in over your head with her care requirements!

I suggest you pick up a copy of the book Understanding the Dementia Experience by Jennifer Ghent-Fuller on Amazon so you can learn about dementia and how to deal with your sister and what to expect from her.

Have a Plan B in place for when she becomes too much to handle and you can't do it anymore. Hire in home help on a schedule to give you respite, is one plan, and placing her in Skilled Nursing care with Medicaid is another, if money is tight. In home care has to work for BOTH of you, not just your sister. You can't give up your entire LIFE because she wants you to, that's unreasonable.

Play it by ear but be realistic.

Best of luck to you.