trust就是一个合同, 所以language里面的nuance对结果影响会很大. 所以我建议你去找加州的attorney. 以下几点可能会比较关键:
1. What duties and obligations the granparent, as trustee, has? What are their discretions?
2. When will the trust terminate and how?
3. Is there an articulated purpose of the trust? If not, what is the primary purpose of this trust in light of all the trust provisions?
4. who are the beneficiaries, including remainderman, and what are their right?
I don't understand why you cannot move in with the kids, as his/her sole guardian. Do the grandparents say No? If not, you may as well pay your rent to live with the kids and the grandparents. Since the trust allows the grandparents to live there, I don't think you can evict them without any court order.
In addition, I don't quite understand the child support issue. If the mother is deceased, why child support is still at issue, unless the trust was established as part of the divorce settlement? Then you mentioned that you were not divorced after all. I am very confused as to the background of the trust.
It is impossible to provide legal advice this way and I don't intend to do it. Let me reiterate this, your best bet will be a competent attorney, if you believe it is worth it. It's totally a waste of your time to ask for legal advice here, as your case almost totally hinges on the trust, without which nobody can provide any meaninful advice.