Society vs trust

Hello, There is this religious society that has formed an educational trust, for administrative purposes only, of a school. The trustees are 7 independent trustees, plus 3 post-holders of the society. Until now, the trust made decisions by majority voting of trustees. Now, the 3 trustees from the society demand that their resolutions do not need majority vote, since they come from the 'parent' society that has formed this trust. Nothing such is mentioned in the trust deed. Help!