I don't know if this is the correct forum for this. There are a lot of fare sale during the holiday season. Unfortunately they are broken up by the holidays and typically requires weekend stay. In order to take advantage of fare sales and meet the min stay requirements, I want to cross-book my trips:
Trip 1: Leaving day 1, coming back day 20
Trip 2: coming back day 5, leaving day 16

I am told by a friend that cross-booking is not allowed. Is that true? If so, why?Should I book trip 1 first, then wait a little while to book trip 2?

Thanks.