California Probate Code Section 16013 states that if a trust has more than one trustee, each trustee has a duty to (a) participate in the administration of the trust, and (b) take reasonable steps to prevent a co-trustee from committing a breach of trust or to compel a co-trustee to redress a breach of trust.
In other words, except possibly in a circumstances where the terms of the trust provide otherwise, co- and multiple trustees need to sufficiently get along and make decisions with which they both or all agree as the case might be. This can be accomplished, of course, but co- and multiple trustee situations also can create challenges and difficulties, and work better when communications are good with proper demeanor. If you are in a co- or multiple trustee situation you need to act accordingly.
Dave Tate, Esq., San Francisco and California