Actually depending on your party makeup/skill level it might be better to kill at least the babies present at the start. It's not difficult to kite the bosses and kiting avoids their worst moves. Kite or Sleep (sleep potions and the sleep spell seem pretty accurate but it's not a guarantee) the boss and have someone keep it busy while the rest of the party gathers up the babies, each taking one and using AOE ws/spells to get rid of them. You can have the healer(s) rest up some mp before taking on the boss without worrying about too much damage being taken.

After that point though, it's better to just go for broke and focus the boss itself while using AOE ws's to try and kill adds as they come while still damaging the boss. I haven't paid attention too well so I'm not sure what triggers the boss calling more babies, but if it's based on the boss's hp you could kite or sleep it while your party deals with the adds.

These methods are safer but take more time so I would only really try them for Antares and Sargas where you're likely to have time to spare. A slower party will get overwhelmed by adds if they are not dealt with and it's really bad to wipe at that point because all adds that are there when you wipe will still be there when you run back to the boss. If your party is durable enough or you're low on time it's best to just try and focus on the boss at the start, though.