You make them Priests to live a life attoning for the sins of the father.Brownbeard said:your bastard children might be able to inherit. give them land and a title. that might trigger an event that will legitimise them and remove the bastard trait...
on the other hand i prefer that they do not inherit due to their low stats(they are useless cousins after all and have debiliated stats). i prefer to make them priests and future bishop material