Legal Question in Wills and Trusts in California

Depending on the terms of the trust, either the majority of the trustees or all of the trustees will have to agree on how to distribute the property. If the trust allows for "non-prorata distribution" (probably) and If there are sufficient liquid assets, you can allocate the house to just three of the siblings and a correspondingly larger share of liquid assets to the sister who doesn't want to be involved in the house. You can sell the house and distribute the net proceeds. Or you can just distribute the house to all four of you. If you can't agree it will be more complicated. Note that parent-child transfers are exempt from reassessment in CA, but sibling-sibling transfers are not.

this depends upon the language of the trust agreement. you and your sisters should retain a qualified attorney to advise you with regard to the many duties and responsibilities of trustees of such a trust after the trustor is deceased, as well as answer questions such as this specifically and with full knowledge of the facts of the trust and its assets.