Auauau, nonono, actually I figured it out this morning o~o
Apparently as long as there's an event with the same ID on the map that the event is taken to, it's all good~ My dependent was 21 so most of the maps I tried it on didn't have that many. Made some spares and it worked great.
Map boundaries I'm sure are a problem. I'll just keep it in mind to avoid those.
As for the roaming, good to know that wasn't my fault at least. \o/