Edit* A better solution would probably have people not chained stay in real time while people that are chained together join the fight at the same time.
This won't work in most cases. If you are sneaking around to ambush enemies, most likely you unchained your characters.
Bombs, spells, and abilities that would kick you out of stealth will do there feature like intended going into combat. So say I have Gale shoot a fireball into the characters already in combat, the fireball will apply its damage and Gale will roll initiative and act on the next turn.
Except if combat started because of a dialog and your character didn't roll the highest initiative you are now in situation when your real time party members have to use there ability faster than AI notises them. What we are geting is your real life reaktion time affecting gameplay in a TURN-BASED game.