Help with custom cup

Hi,

I’m currently working on an Australian Database & I need some help creating an FA cup style competition. I can create the comp no problem using the in game editor but what I’d like to do is have the top 24 teams come in at a later stage as they do in the FA Cup but I just can’t get my head around the maths. I have 582 teams & 10 cup rounds (including Final & qualifying) I’d like the top 24 to join about the round of 64 or 32 although anywhere is fine just as long as they get a few rounds off. I’d be even more pleased if say the next best 48 or 64 teams come in a round or two earlier but this is not crucial. Can anybody help?