I realize this is all hypothetical and all
but did you have an opportunity to read the entire Trust document? Many times there is a clause in the document that essentially states that if any of the beneficiaries of the Trust contest the Trust they are automatically cut out of any disbursements. It doesn't seem fair but it prevents one beneficiary from delaying the administration of the Trust by means of a lawsuit. The senior lawyer may have convinced everyone that it would be in their best interest to take what there was instead of spending it on lawyer fees. A Trust can spend $100K on lawyer fees and admin. costs quickly.
You still said this.....
The agreement was basically the same provisions for the beneficiary as what was in the original trust, with a few things from the amendment that was not signed thrown in.......so things didn't really turn out much different than the Grantor intended.
I was an administrator for a Bank Trust department for five years and these kind of situations happened all the time.