Some more advanced ideas:
1. Multiple disguises that can be added or removed at will, allowing alien Sim to choose between different identities.
2. Seperate relationship panels for each disguised identity. These would then be merged if found out, with a result based on the total combination. All known identities would be listed in Sim profile.
This would make deleting an identity a destructive action akin to deleting a Sim, as it would remove all relationships that Sims have with that identity.
Nevermind, probably too messy. It would be cool for other Sims to think the different identities are different people, but it would make it impossible to properly represent the alien's own feelings towards other Sims. So the relationship panel will probably just keep the current behavior of maintaining a single entry, which simply displays the current active identity.
Listing the disguise identities of known aliens in Sim profile would still be neat though.
For some of these to be functional though, possibly including seperate names and gender, disguises would probably need to be rewritten to function as seperate hidden Sims that the alien Sim is replaced by when disguised.