Should I leave money (providing I have any!) to both my son and daughter knowing that if she dies all money goes to animal shelter?

My single daughter plans to leave her money to a charity that takes care of animals and not to her brother or his two daughters. She has never been close to her brother and hasn't seen them in years although we all live in same city. That's because she chooses to work on every holiday and almost all weekends--she is an RN in a psychiatric hospital. Right now all of her spare time goes to the care of her father, from whom I was divorced 48 years ago. He has been in nursing home with Lewy Body dementia for over 2 years. My son goes to visit his day on Father's Day and birthdays, that's all. The two kids will split any money left over when their father dies--he has about $1 million in stocks, which probably won't last more than 10 years at current rates, but surely he won't last that long--he is 84 and in good health except for the dementia. He can't walk or even sit up for long unassisted, but he can feed himself. Whatever money is left after he dies will go to our two children.

I myself may develop dementia as I carry an ApoE4 gene, and at 81 am constantly misplacing keys, cell phone, and having hard time remembering names. My question is, should I leave money (providing I have any!) to both my son and daughter knowing that if she dies (she is very overweight, never sees a doctor and has arthritis in one knee) all money goes to animal shelter? I do intend to leave something for my niece (to whom I am closer than I am to my kids) but not to my younger sister, who says she is leaving nothing to her daughter, my niece, from whom she is estranged. My sister's husband is an MD and they are fairly well off. I am re-writing my will etc next week but don't know yet who I really want to be financial POA. My daughter is definitely the one to make my medical decisions since she is RN and will definitely honor my request for no feeding tubes, etc. My thought is to make them both financial POA in event I am incapacitated. For executor of the will it doesn't matter if they are joint (but able to act without the other's permission) since all of the big bucks have named beneficiaries.