I'd hope that when you bought each ticket they'd have assigned them to 2 references ie yours and your dads, they seem to have sharpened up on this in the past couple of seasons, so effectively you'd both have at least 3 games each....
As for the max 6 tickets per booking I can only imagine that's with regards one caller using 6 valid references to get tickets per call, not sure a) why they'd linit that, and if I'm even right there, don't quote me!!
Might be worth a call to them just to clarify what you and your dad have on record for this season...?