the reason spawning them doesn't work is because its not tagged as lonas baby and is a different baby altogether
i am not the creator but he has assigned me to be moderator here to keep the peace. and relay information from him from time to time.
as for getting abomination rebirths its easier to just not finish the halberd quest east of doom fortress and letting the spider abomination that infinitely respawns grab you over and over till status is full then you just wait at nearby beach
since you can just go survive at the beach or go stay at the doom fortress inn although its wise to bring abortion pills and use one of them and a blue potion at seedbed 10 to test if its abomination or not since a non abomination will die from that combo of drugs one after another