Your child will not change externally, but will have the option to Remove Disguise and Alter Disguise after that. Traits.remove_trait trait_OccultAlienPart I went through the source files for the sims and found the correct names for the traits and did some trial and error. Your child will be a full alien after this. I don't know if this still an issue for you, but in case anyone still has this issue I found a solution, actually two solutions.
