I hate to be that bearer of bad news, but you may not be able to force him to share the money from that account. If the account was in both of their names and titled as joint tenants with right of survivorship, then all of the funds became your brother's property when your mother died. If that is the case, he does not have to share that money. He may still want to share it, however, to honor his mother's wishes; but he would not be legally obligated to do that. On the other hand, if the account is only in her name and he just has check signing privileges, then he would be obligated to distribute the funds to her heirs. You'll have to try to find out how the account was set up.