Heavy check in bags are always with me up at the counter! We travel to Indo 3-4 times a year and we have never had to both be at the counter so sorry you have to, especially with kids! oh and when I have a porter helping me I always have my extremely heavy carry-on with me at the counter. It has never been weighed in Indonesia. I have had them take it from me at the plane if it is an ATR and then it is always at the bottom of the stairs when I deplane.It has never worked with my family (2 adults 2 kids) - You can't imagine how disturbing it is to queue with young kids. Maybe they do group check ins for adults and/or bigger groups - I don't know.
In any way if 2 people are traveling (as @Seattle Shaun seem to be doing) having one of them doing the check in and the other one stay further back holding the (heavy) check in bags doesn't seem to be a good tactic.