Read of the pregnant animal bug but did not yet see it happen.
Then arranged for a marriage party, but the bride (living at another lot at that time) was not willing due to the bug (got the notice).
Moved her in with Tombstone of L&D (read that too when I read about possibilities to get around the bug, I rarely use the in-game modder so did not know this feature before).
She was added to the family but had only 5 want slots and 1 lock (before that she was a graduated fully grown up sim living in the NBH)
Added 6th slot and second lock with TwoJeffs Uniadjuster.
Next time I entered the lot I noticed she did not age anymore (Feature of using the Tombstone? - I donīt know as I am lacking the experience).
Solved this problem by having her move out, brought her to another lot, invited her and asked her to move in again (no pregnant animal then ..)
But since then she has 6 want locks....
Ended up confused.
Next time, another lot, other sims, similar situation (I HAD to know if this bug is consistant...). This time saved the lot with the party which had already started, moved the bride out from her own home lot and added her to her new family from externally. This spoiled the party which was broken, but got me around the bug without further problems.
So now what really is the best way to get around that bug?
And is not aging anymore a known feature of the movein with the Tombstone of L&D?