All breeders. What does 'cross cover' actually mean?

[Fools Motto]

I know this may sound like I'm a bit dim, specially as I work on a stud! BUT, if you don't ask you don't get.
Anyway, one of our mares is proving to be a tad tricky to get in foal, and our next plan of action is to 'cross cover' her. Hence question! And how will this aid her chances of being in foal?

 

[Laafet]

Not sure how it would help in your circumstances, but with TBs if you get your mare ready, scanning her until the follicle is big enough to ovulate, cover her then she doesn't ovulate for a number of days and still has a viable follicle you 'cross cover' (basically send her back for another cover) until she does ovulate.