2005 California Probate Code Sections 15620-15622 Article 2. Cotrustees

15620.  Unless otherwise provided in the trust instrument, a power
vested in two or more trustees may only be exercised by their
unanimous action.
15621.  Unless otherwise provided in the trust instrument, if a
vacancy occurs in the office of a cotrustee, the remaining cotrustee
or cotrustees may act for the trust as if they are the only trustees.
15622.  Unless otherwise provided in the trust instrument, if a
cotrustee is unavailable to perform the duties of the cotrustee
because of absence, illness, or other temporary incapacity, the
remaining cotrustee or cotrustees may act for the trust, as if they
are the only trustees, where necessary to accomplish the purposes of
the trust or to avoid irreparable injury to the trust property.