This is the English Language
and from the OP's description, her father is wanting to make changes...her mother is being the difficult one.
Since the monies were in a joint account anyway, all the money would be the property of the surviving spouse to do with as she pleased. Apparently, the mother has reason for doing what she is doing - like the OP being a PITA, borrowing money & not paying it back, etc.
When asked by HG in another thread about title to property that the OP co-owns with a brother, no reply was given. The problem was about cutting and selling trees.
Wanting and wishing to do something for someone implies cooperation in helping that someone achieve the task...no?...
...and since this is clearly different from a situation of contesting a will...comparison doesn't apply at all.
1want
Pronunciation: \ˈwȯnt also ˈwänt & ˈwənt\
Function: verb
Etymology: Middle English, from Old Norse vanta; akin to Old English wan deficient
Date: 13th century
intransitive verb
1: to be needy or destitute
2: to have or feel need <never wants for friends>
3: to be necessary or needed
4: to desire to come, go, or be <the cat wants in> <wants out of the deal>
transitive verb
1: to fail to possess especially in customary or required amount : lack <the answer wanted courtesy>
2 a: to have a strong desire for <wanted a chance to rest> b: to have an inclination to : like <say what you want, he is efficient>
3 a: to have need of : require <the motor wants a tune-up> b: to suffer from the lack of <thousands still want food and shelter>
4: ought —used with the infinitive <you want to be very careful what you say — Claudia Cassidy>
5: to wish or demand the presence of
6: to hunt or seek in order to apprehend <wanted for murder>