I found this info on the internet.
Disinheriting other beneficiaries - If the original owner adds one child to an account but has other children they want to inherit the account, then by adding one and not all of the children's names the owner will have effectively disinherited all of the other children. And even if the surviving joint owner agrees to give the other children their fair share of the account, care must be taken to avoid any gift tax consequences.
We figure that if there is enough in the account when mom dies, Sis can take us all to a nice restaurant. Otherwise we'll go to MacDonalds and raise our plastic Coke cups in a toast to a great mom.
Mom "loans" money to the brother who is disabled. All the rest of us are glad we don't need that kind of help, and we'd never expect him to repay the loans. The amounts are small, to get him out of pinch when his car breaks down, etc. She is not supporting him -- she couldn't affort to.
None of us have ever expected to inherit anything, except items of sentimental value. The more I read these forums, the more I am very, very glad about that.