My father (92) has advanced cancer. Would a DPOA or POA benefit him regarding care?

Well done Sandy, Must be quite a relief!!

Bringing up the advice directive was made a little easier with the help of Jan. We were at dads oncologist appointment filling out his paperwork, it didn't come in the mail, the last page was to be signed by him and his spouse or guardian that they were aware they were responsible for any balance owed that the insurance didn't pay. Dad signed it and handed to Jan, she read it then in her normal loud voice said "I'm not going to be responsible for this!" This upset my dad he told her to just sign it. (The VA is paying for this we've told her this their also paying for the nurse 2xs a week, PT 3x's a week and the aide comes daily) We just told my dad that it was fine she didn't have to if she didn't want to, dad was upset an embarrassed she caught the attention of the whole waiting room. Then of course she had to start crying and the subject was dropped, so when I took them back home I brought up the advance directive wrote down everything of how he wanted it then wrote my name in he asked about Jan I told him I didn't think she was going to be emotionally able if the time came he was good with that and signed then I got the apartment managers they read and signed it as witnesses then made me copies. I'm just glad that's over

We are dealing with a blended family, step dad in hospital situation right now. Our families are not large, but the issue of kids (of any age) being more concerned about their own parent than the step parent are playing out.

Her kids need to know that your Dad is gravely ill. He will no longer be able to provide care for her and is likely, with the cancer having metastasized, to pass sooner than later. It is the job of her children to support her. It is your job to make sure your dad is getting the medical care he needs and is kept comfortable.

I am not sure from your post where they are living and what level of care they are currently receiving. Can your step mum continue to live there? Howis it being paid for? Who is paying?

You need to have a conversation with your Dad about his final wishes, is his will up to date, who is the executor etc.? You may or may not need to get a healthcare POA, if your dad gives verbal permission for you to talk to his doctors, you may not need it.

Who currently is handling their finances? If Dad is blind who pays the bills? Do you or your sister have a list of your Dad's accounts? Are the accounts in joint name? Whose name, you, your sister, your stepmum, her kids?

Have now talked to 3 of my 4 siblings we've agreed after tomorrows appointment we will discuss it with our dad Jan his wife will have to go for a walk if she can't handle his kids discussing this with our father cuz this for his care and wellbring

Your difficulty seems to be not with your father but with your stepmother. For that is what she is, no matter how late in the day their romance.

Given the severity of your father's illness and his age, I think it might be difficult for him to cope with creating POAs while fending off his tearful wife.

You could ask his doctor to insist on seeing him in private, and ask the doctor to ask him whether he wants to spare his wife the POA and health care responsibilities by appointing new proxies. But the doctor won't agree to this if he thinks it's going to burden his patient unreasonably.

On the other hand, he might agree to ask if it's going to make medical decisions simpler. But your father would still have to be up to the job.

Does your stepmother have any family of her own? Where are she and your father living?

Absolutely he should have a POA medical and financial effective immediately.. It sounds like his wife should too. Perhaps she should have an evaluation as well.
JoAnn's idea to take him to lunch and do it apart from her is a good one,

I am sorry about the cancer diagnosis. What a difficult situation!

I would ask Dad to assign someone as his Financial and Medical POA. Make sure in the medical POA he lists what he wants and what he doesn't want. Take Dad to lunch and have someone sit with her. This is serious. Dad should probably start Hospice. So sorry.