New teams

So my boss is in Ohio, bringing home new teams of horses. The teams have been together for over a year...just working together...no switching around or anything.
We're trying to decide the best way to get them on the streets. Should we be driving them together? Or should we split them up and drive them with other horses?
I'm really leaning towards keeping them together, just because that's what they're comfortable with...and being in a new place...i think that would offend them more being with a strange horse. Any thoughts? opinions?