Changing the alternative form of my occult Sim also changes the normal form

Problem

• I can’t change the dark form of my Vampire individually anymore. Every change carries over to the human form.
• I created a mermaid, but when I change the human form, the mermaid form is also changed.

Solution

Since Patch 1.52.100 there’s an option for Vampires and Mermaids to link both forms together. Linking them is the default.

Click on the chain icon to link  or unlink them

Once linked all parts that you have clicked will be changed together automatically. You can also copy over certain parts from one form to the other. Like with the linking only the parts you have chosen will be copied.