As I stated in the similar thread, let's not conflate "characters" and "origins".

What we have are characters.

What we're asking for is tags for the custom character that reference an origin.

We're not asking for the same level of detail as the characters. Otherwise, we'd be asking for more playable characters.

The evidence so far is that we have tags, but these do not reference the origin of the character. All it would take for a tag to become an origin tag:
A) It is mutually exclusive with other origin tags
B) You meet a character who remembers you, per that origin.

That's the difference, and it's not hard at all.

Beyond that, it's not any harder than implementing any other tag. Actually, it's easier. It's mutually exclusive with other origins, so you only ever have to worry about the PC ever having one of the origin tags at a time.

Of course, you could go all out with it by taking it as far (or further) than Dragon Age: Origins, but we all know that all player characters start the game in the one place, and I doubt anyone here is expecting anything so epic.