Not sure really.
Guess we shall find out this weekend.
I think it brings you back in at last save so you would have to send the invite,
and you would have what you built up till your save.
Although my Ai was still building while I was away, it would revert to when I last saved and exited for me.
Still a learning curve for me and I did load it on my laptop so once I start staying out of town alot I can play on the road!