In a drawing of large assemblies that I have pack and go'd from other places  it seems that as I change a model, move/replace, components, etc. the balloons in the model do not update as I make changes and the BOM tends to get screwed up as well. If I erase the BOM and reinsert it, it usually corrects problems but I also have to reinsert baloons to update reference numbers. I'm just a little confused and wonder if anyone can give me some advice on what to do differently or shed a little light on this subject. Thanks for any help. ZZ