Well, you can go to court and ask that the trust instrument be amended, retroactively, to allow that.  

Your question is very complex, and it depends on trust language, and local law. No simple answer. Here is an article from american bar association that may help you:

 https://www.americanbar.org/groups/taxation/publications/abataxtimes_home/20feb/20feb-pp-lepore-trus...