Legal Question in Real Estate Law in California

Re: eviction, if on title to a house

Probably not. Your question leaves out or abbreviates a lot of legal-language explanation that would be required to give you an accurate and complete answer. However, it is likely that the siblings are tenants in common or possibly joint tenants, in which case each has the right of possession and cannot be evicted.

I repeat this is an oversimplified answer based on too few facts.

Was any lawyer involved in setting up this trust or in handling the estate?

Any cotenant can sue for partition to require sale of the property by court order, with division of the net proceeds to follow. However, removing a cotenant already in possession cannot ordinarily be done by eviction. An attorney would have to review the trust documents and other instruments, facts and circumstances to draw sould conclusions about your relative rights.

Re: eviction, if on title to a house

It depends on how title is actually held. You appear to indicate that title to the house is both a trust asset and a joint tenancy asset. Consult a probate attorney as soon as possible to help you resolve the issue.