Is this even possible?

Hello, all. I'm trying to create an historical league that starts in the year 2000 that also incorporates all the other real-world leagues.

The game imports all players as though my game's going to start in the year 2000 without issue, but when I add the other leagues (Nippon etc) it resets the game date to 2017, so I change the game date back to 2000.

When I enter the actual league, all the players from 2000 are there, but their ages are as though the year is 2017.

Is this some kind of oversight with the game? I've tried multiple different ways to make this work. It shouldn't be this difficult to start a game in the year 2000 with ALL leagues intact.