Stuck

If you want to hold off on playing your main save until the new infants are added, but still want to do story telling with Erik, you could do a “What if…” save, where you explore taking him into pursuits other than music. “What if Erik became a doctor? An astronaut? A writer? An Actor?” You could set it in an alternate universe, or just frame it as Erik’s musings about where his life might have gone if he had chosen other career options.

Something like that could be short term fun until the new pack comes, wouldn’t affect your main save, and you can easily move back to your game at whatever point you choose when you’re ready.