Legal Question in Real Estate Law in California

Yes. You should have cross-complained against them when you got sued.

Probably. If the other children or parents were not named in the victims' lawsuit, either as initial defendants or upon their later identification as "Doe" defendants, they probably should have been haled into court by way of a cross-complaint. You don't say how far this case proceeded in court -- all the way to trial, or settled beforehand -- or whether you were represented by counsel. I assume the case is now dismissed. In that case, it is probably too late to get the others legally obligated (by way of a judgment against them). It is not necessarily too late to assert, privately, that they have a moral obligation to share the costs.