My short answer would be yes, they can be added together (with some likely & possible problems .)
I have seen many tanks with this combo, (along with Lelupie) & they work out fairly well & are loosley from similiar water parameters (fronts being in deeper spots along the coastlines) in the wild.
HOWEVER, over the years I've noticed that the problem with the juvie front & brichardi mix, is that the brichardi can be rather aggressive & nippy & could destroy the extended fins on frontosas by picking at them.
I would also mention that b/c these two fish are drastically different in size, many times the brichardi in a tank with fronts are MATURE specimen where the fronts are juvie & the aggression of the adult brichardi can get to be a little much.
I personally have brichardi ( a group of 5 ) with my fronts & I think the key to the safety of the juvie fronts is a large aquarium, where space isn't as much an issue as some smaller ones.
Just MY Experience.
gjx