Thanks. I wasn't expecting this at all but once I got over the initial shock, I am relieved we can finally get going and not deal with MS getting in the way of herself.
One reason why I wasn't expecting this was that initially my attorney thought we would have to go through the process of getting her removed but he found a clause in the trust that allowed for designation of a special trustee. This can be very specific, naming specific tasks, which is great because one thing I did not want to assume was the financial responsibility for the estate, like paying bills, etc. I wanted no liability in the event of any mismanagement. This way I can handle the house related stuff and MS can handle the financial stuff, answering for what she has done so far. Once the house is sold, the money goes into the estate account which MS manages. Could be another issue in getting her to disburse but that's for later.
On the inlaw side, SIL has had quite a bit of money given to her from MIL / FIL, especially after both came into sizeable inheritances after grandparents died. For a long time DH complained that if his spendthrift parents die broke, she would have gotten her inheritance "ahead of time". I point out that his parents' money is theirs to spend as they see fit, they were and still are of sound enough mind. DH is long over this now but I know that if the situation was in reverse, SIL would be the one chasing the money he got after they passed.
My maternal grandmother died completely broke, all that was left was personal belongings. It made it all very easy. I had a coworker tell me that he encouraged his mother, after his father died, to live her life and spend her money, after she expressed concerns about leaving some for him and his siblings. His attitude that if she left little or nothing that would be the best thing, no drama, no hassle.