My daughter in law is bipolar (but takes her medications religiously). She also has no concept of money (mainly due to her upbringing - her father is a lawyer and she's just never had to worry about money). Being married to my son - a sailor - has been a very rude awakening. I kept telling her that she was marrying "down" in life, and I wasn't really kidding.
When my son was deployed, they both came to me and said they wanted ME to handle the money while he was gone. I only did so because they BOTH asked. I had complete control of my son's account, and she did not have the passwords, access, nor was she listed. She had a separate account to use to pay bills. I knew what rent and utilities were, and we (all three) came up with what would be reasonable for food, gas, spending, etc. All other bills (insurance, car payment) were automatically withdrawn so she didn't have to worry (we tried getting rent, too, but that wasn't possible).
Any time she needed extra, she had to come to me and ask for it. I never denied her anything, but it made her think twice before spending. She had a credit card, but it was to be used only for emergencies and she had to clear that with me first. She actually froze the card - put it in a block of ice in the freezer - to stop herself from using it impulsively. She asked people for gift cards for Christmas and birthday and used those as her "mad money".
Did this teach her money management? Not really, but it guaranteed that she didn't drain the account or run up a huge credit card deficit during the months my son was deployed.
Since he's been back (but they are still living in separate areas) he's given her a bit more leeway, and she's overdrawn "her" checking account at least twice that I know of. He'll be out of the Navy soon, so it's going to be interesting to see what happens when they are living day to day together (my son is CHEAP, always has been).
Anyway - I guess the point of all my rambling is, yes, my daughter in law is also sick. But she realizes her limitations, and she is willing to ask for help. Did I sometimes have to be a little hard nosed with her? Yes, I did. Did she resent me for it? Probably. But it was what they decided, and I held her to that.