Mermaid/Vampire hybrid problem

My mermaid Sim got abducted and had alien twins. I just aged the twins up to teens and am having all kinds of problems with them. Every time they swim, their alien appearance completely changes and I have to restart the game in order to get their original appearance back. Is the only way to fix this still to remove their mermaid aspect? I love the idea of their being both mermaids and aliens, since that's what the game gave me. :)

@kalaksed thank you for your helpful information! How do I make them half-aliens instead of full aliens?

"kalaksed;c-17401146" wrote:
@Rouenpucelle just had to go into one of my households to double check that, the trait is trait_OccultAlienPart, you'd have to remove trait_OccultAlien

Thanks so much, @kalaksed!

I had a mermaid-alien. Was fine till she reach kid then it was a mess. While editing her in CAS, saving, and going into game, it completely deleted her. I did NOT delete her, the game did. Was gone from the generation tree, absolutely everything. I ended up making a sim that looked close to her and acted like nothing happened. Out of fear the couples second born would have the same issue, I gave her up (definitely would have done that differently now).

"Kersiexx;c-17402049" wrote:
I had a mermaid-alien. Was fine till she reach kid then it was a mess. While editing her in CAS, saving, and going into game, it completely deleted her. I did NOT delete her, the game did. Was gone from the generation tree, absolutely everything. I ended up making a sim that looked close to her and acted like nothing happened. Out of fear the couples second born would have the same issue, I gave her up (definitely would have done that differently now).

Oh no! How devastating. I recently had a mermaid woohoo with an alien. Their child is a baby right now, and this worries me for when she grows up.

It would be great if this glitch were fixed. I didn't intentionally create alien-mermaid hybrids, the game did, so it seems like the game should support them. For now, I'll just save a lot while I play. :)

I have a question for Kersiexx.
Do play with mods, cc or Mcc?
The reason I want to know is that I only play Sims 4 without any of the mods, cc or Mcc & I just made two supernatural couples in my game.
I was hoping for a natural hybrid child from each couple just like in Sims 3.

I thought they fixed the risk of hybrids occurring. I have the lot trait on a dark ley line and my sim got pregnant by Simeon Silversweater.
She was born a spellcaster/vampire. There is no way to set her darkform, she only has one form accessible in CAS and she has no vampire or spellcaster UI. She can access her spellcaster points but not her vampire points although she has both a vampire and magic pie menu.
edited for image:
https://i.imgur.com/udO9Lyr.png

The same thing happened to me. I ended up losing the whole dark form of my vampire-mermaid sim trying to fix it... Is there anyway to stop the glitch or are you forced to max the vampire lore skill and make the vampire cure to fix it/eat mermaid kelp twice?

I wish they would fix the Mermaids. They are the only occult trait I can't add onto my sim. I have noticed that only my Alien/Spellcaster/Vampire hybrid sim plays well. FYI, I only use the traits codes cause I only play vanilla.