What can long distance siblings do to help?

Have her come so that you can take a vacations/breaks. It doesn't matter that hands-on caregiving isn't her "specialty". She can learn, especially if she was an exec. And it might be more "tolerable" to her if it's only for a long weekend, or a week or two. You need breaks and finding a replacement is time-consuming and expensive. Train her into that role while your mom is easier to care for. I read your comment that you'd prefer your mom went to your sister's, so if you can make that work (including financially) that'd be so good for you...but as your mom declines will become more work to prepare for that and more disruptive to your mom. Whatever works so you can get regular breaks.

Also, in our family my elderly in-laws were broke so the out-of-towners were very happy to send necessities like clothes, etc. They would make care packages with goodies in them, or sent cards, and made more calls to my inlaws just to chat with them.

So many things can be done online and by phone and email. Food Shopping. Prescriptions. Making Appointments. Monitoring cameras. Routine phone calls to parent. Holiday /birthday shopping. Taxes. Reminders for filter changes or other home maintenance chores or repairs. Research of meds, medical conditions, caregivers, medical providers etc. paying bills, balancing checkbook.comparing insurance policies, monitoring lab work. Having someone intimately involved with the minutiae could be very helpful.

I second the phone calls. It took me a long time to deal with certain phone calls.

I would also say to call your mom if she has a good relationship with her. I constantly heard about siblings that barely called.

My mom sends out cards for birthdays and Christmas. Due to her Parkinson’s disease, she could no longer write so I did it. So, she could shop and mail cards if your mom does this too.

Visiting every so often so you can take a break!

I would have very much appreciated if my sister-in-law would have offered to assist me by making phone calls. Simple as that! MIL was in an ALF for 6 years, and currently a SNF (4 years). Sister-in-law would always defer to me because I am local. Baloney! Administrative calls are administrative calls. I spent hours each week on the phone fielding problems.

Good luck and hang in there!

If you pay your LO’s bills by checking, she can have the bills sent directly to her and pay them.

My LO’s TWO POAs have a checking account in her name, listing each of us as an independent POA.

You could also set up a credit card with the LO and sister I think, with the assumption that the credit card be used for NOTHING EXCEPT LO’s expenses.
If you choose to explore that option, I would check it out with a lawyer before doing it.

I’m also my LO’s designated payee for her Social Security, and her check goes right into the POA account.

As you’re probably aware, you need to be fastidious with keeping LO’s funds and care expenses separate from any other bills.

Hope my comments might be helpful!