Legal Question in Wills and Trusts in California

You need to see your mother to find out what is really going on. Your sister may have 'buttered her up" but not likely to the point that she would disinherit anyone she considers a relatively good son. You have to find out if it is elder abuse or just her talking your mom into believing she needs the money more than you do or that you have already gotten you inheritance through gifts so she should get the rest. Parents do not think rationally when it comes to their Wills; bad kids are often included and given more than they deserve.

You do not say whether the trust was irrevocable or not. If your mother followed all the terms of the Trust then you can so nothing about that. Did your father have any separate property, as that would pass absent a Will to the three of you. If your mother is of sound mind, she can make what ever changes she wants. Offer to pay the cost of seeing an attorney for him/her to do some estate planning, including maybe setting up a trust for your sister. If your mother will tell your sister that she is going to do that, the the both of you should go with your mother to tell the attorney that facts of the situation and then let your mother speak with the attorney in private and agree not to tel either of you what was decided on.

Good Luck.