Years ago (prob around 15 years ago), DM set up a joint savings account with me. At the time she said she and her mum had one and that I should consider the money mine. It's a 40 day notice account. Early on I put some money in, but she put in the lion's share. When I was a king big purchases (e.g. New kitchen, car) she'd say to take it from that account. I never did - too much hassle to withdraw money. Over the past 10 is years it's just sat there, I've put in the odd £50 to keep it active. But it's gaining no interest now, so I wanted to move it to another account. When I mentioned it to mum to get her permission as joint account holder she agreed and has written a letter to bank to that effect.
Anyway DB is visiting for a few days and he mentioned how dm is anxious about the money, that she can't remember where the money came from, and that she wants to split it between him and me.
Aibu to disagree? It's not all her money to decide what to do with. If I'd used it when she'd suggested then there'd be very little left. There about £13k in it, mum will have put in around £6k I think, but have no statements from when it was opened. DM is terminally ill. If I hadn't mentioned the account to her it would have just come to me when she dies. She wants it sorted out and wants me to give £6.5k to DB.