Legal Question in Wills and Trusts in California

You need to discuss this with a probate attorney. More likely than not you will need to file a probate action.

Consult a probate lawyer to file a petition to probate the property into the three of your names.

I agree. You are not on title so you are not able to sell the property. The only way to get on title is to comply with the available transfer procedures. This most likely means a probate to obtain a recordable court order placing the property in your names. See a probate attorney for specifics (and take him a copy of the existing deed if you have it and the death certificate).