can a lawyer in California, acquire an interest in real property he is litigating?

I see it this way: clearly the siblings hired the attorney and after the attorney got into court they told him they had no money to pay him for his services. If he asked, and I don't know he did, for someone to give him an interest in one of the properties to pay his fee he could have been joking, and frankly he could abandon these folks if they continue to say they aren't going to pay him because otherwise he will have to sue them for his fees. You saw nothing from the attorney to the affect of acquiring an interest in the property did you? Well then why are you asking your non-authentic question? Right away you want to sue when there is no reason to sue. Just means the attorney will have to put a lien on the property to get his fees. Surely he could have guessed the property is an asset of the estate.

I don't get what you mean the "mother did not deliver the deed". That has nothing to do with anything.

Conflict of interest. The lawyer can be reprimanded if not disbarred for this.

Check the state bar ethics rules. Sorry about the reading and thinking.