Legal Question in Wills and Trusts in California

It depends on what the trust says regarding decisions. If all three are required to approve a payment, the two trustees may have to file a motion with the local court to have the 3rd trustee removed as trustee.

you should retain a qualified attorney to provide advice and assistance regarding the fiduciary duties of the trustees and issues such as this regarding administration of the trust.

To add to the previous attorneys' advice, most trusts do not require all co-trustees to act together in all matters. However, as Mr. Jordan advises you, it is the language of the trust that controls this. If the trust requires that all the trustees must make decisions and act together, then, you would need to file a Probate Petition to have the nonresponsive trustee removed as trustee. You might also try asking your uninvolved sister if she would be willing to agree to remove herself as an acting trustee. If she is unwilling to do so, even if the trust does allow two or one trustee to act, you might still consider the petition if you feel you might run into this problem in the future.