I've had this request 4 or 5 times from various customers. Apparently Solidworks (excuse me) allows you to split 10 bolts on an assembly into two balloons of quantities 4 and 6, or three balloons of quantity 2, 3, and 5 etc. This is not a quantity override, its fully linked to actual assembly QTY and the quantities can be shared between as many balloons as desired. Tricky to implement I guess, but it'd be huge for many people I think. Apologies if this is a duplicate idea.