In state of WA, can a grandparent take minor children from mother with a brain injury - against her will?

I have two minor grandchildren, ages 12 and 10, of my daughter, age 30, who was brain injured by a hospital 5 years ago. She functions, but recently had 3 major spine operations at Cedars Sinai in LA for tumors. She is on multiple meds, loses her balance, has headaches (relieved somewhat by the recent operations) has seizures and is very unreliable. She spends her allotment from the suit against the hospital on dogs, shopping, cars, frivolous stuff. The children take care of the dogs and wait on her. It is a very unhealthy situation. I want to get custody of the children - still in CA with an Aunt - and take conservatorship over her funds before she depleats them all. How can I do this in WA?