USMC's is in equipment/various_USAF.xml.
Engineers's is in equipment/various_engineers_USAF.xml but Engineers's will have problems if you increase the amount of charge.

Right, i increased the sandbags amount and it doesn't place anymore, only the LAST unit can be placed on the ground, thank you nonetheless :)

no problem. Sandbag and Demolitions utilize the gimmicks that AT-4 or RPG-26 throw away after use. So it only works if it's thrown away.

Im sorry for these questions, but this will be more "advanced" one, how do i add Demo_charge for Army rifles squad, this would be so great because i like this class more but there arent any charges for the walls, this would be a big thanks from me <3

You should use mod discussion or DK2 discord, not here

Ok chief