First off, how long have the new ones been in isolation?
Second is your coop large enough to comfortablely accommodate 14 birds for several days?
Depending on your answers I would put the newbies in a large wire crate for at least a couple of days first. This will allow them to get comfortable with thier surroundings. After at least two days put the new birds on the roost at night.
You need to be sure that the new birds have places that they can get away from the others if things get violent (very important).
Keep an eye on them the first day.
Add lots of treats and goodies to keep them occupied that first day.
Ultimitely you will have to be thte judge to decide if it is safer to let them out and run the risk of them roosting elsewhere versus them being stuck inside the coop with a large number of new and possiblely aggressive birds.
I personally would let mine all out after the removing the crate, this allows them to have lots of space to get away and doesn't put the original flock in a stressful position and unusual circumstace of being stuck inside.
