Legal Question in Real Estate Law in California

There is absolutely nothing illegal or inappropriate about it at all. Any tenant in common can sell their interest without so much as notice to the other owners. The only thing that would be inappropriate would be if they failed to tell the prospective buyers that they would either have to obtain the consent of the other owners to sell their interests too, or that the buyer is only getting a fractional interest.

People tell you to get an attorney because you don't know what you are doing. Mr. McCormick pointed that out to you. The other tenants in common can sell their interest to whoever they want, they don't need your permission. They of course, cannot sell your interest without your permission, but you are not in charge of other people's lives as much as you think you are.

While I agree with the previous answers, it also must be asked, "What interest are the selling co-owner and his real estate agent/broker holding themselves out to be offering?" Is it clear that they are offering only a part interest? Is that really all the seller has, or has he acquired, or does he think he has acquired, the right to sell the entire property, perhaps as agent or under a power of attorney for the other owners? Is the property in a trust and he the trustee? The previous answers are probably correct, but at LawGuru we have to allow for the possibility that there are additional facts that would suggest other answers.