8Drywall expands when it gets wet. So it loses its integrity. Which means it will fall apart on its own if you do not remove it. Seeing as it is in your garage its the barrier between fumes from your garage into your kids room. Mold is created when something does not dry out quick enough. So by removing all the wet drywall you have a better chance to dry out what is behind it. Also spray what is behind the drywall with a diluted water bleach mix. Most insulation once wet collapses on its self and no longer does its job it goes too. Sorry. Use fans to help move the air around the spots that got wet. Pick yourself up a moisture meter.
Wood Moisture Meter, Digital Handhold 2 Test Probe Pins LCD Wood Moisture Moisture Tester, Damp Detector Tester for Firewood Tree Paper/Walls Paper/Floor Carpet, Not Include Batteries (Black) https://a.co/d/daaAP0D
When the structure has a moisture reDing between say 8 and 12. You can reclose the walls and ceilings. I have to say no parking in the garage till the opening is sealed air tight. Good luck. It's not an expensive fix just a pain to do.