Let us know how that works out, if you could. My expectation unfortunately is that especially without mods (ErrorTrap in particular), sims created and played with LN in play aren't going to function without it. For example, they will have now undefined skill levels for the piano, drums, and cello. Even if these sims never touched those musical instruments and were thus all at Level 0, the game wouldn't really know how to read or what to do with such data now.