How do i set up an shared bank account for my parent on Medicaid?

My mom is on medicaid and lives in a nursing home. Medicaid takes all but a few bucks of her income which doesn't allow for much. My two siblings and I want to set up an account that allows us to pay for some things beyond what the nursing home can provide. Ideally, the three of us would be able to contribute money to that account and all access it as needed. We'd prefer our mom to be able to use the account to pay for a few things like her cell phone, occasional take out meals, etc. However, if she can't be on the account for Medicaid purposes, we could manage by making sure we pay the helpers using other means (venmo, cash, etc). My mom still has a credit card that she uses and we pay it off but I'd like to use the new account to do it as opposed to taking turns doing it now and trying to keep it even.

I know she can't have anything in her name. Some of the money we'd deposit would be cash and I'm concerned that could cause a wrinkle if it's too much. A friend suggested an LLC and to open a business account so my siblings and I would all have equal access to it. In the event of my mom's passing, we could close the account and spit it up. Then it seems I'd have to worry about filing tax documents for the LLC. Maybe I'm overthinking and a simple joint account would work.

Any guidance is appreciated.