The problem both sides are having is the lack of transparency and communication. I haven't bought anything for USA or MYS, so not really familiar with their protocols or procedures (maybe some of it is already in place, and if so, maybe needs updating / tweaking to be viable).
Back when ExcellPurchase was running, part of the instructions / terms of their deals were:
4) Right after making the order put the order number into the portal
5) Once your order ships, add the tracking number to the portal.
This helped them monitor what the projected sales / commitment volume is, and know who their loyal customers were.
There's no reason why other groups don't make you do this (if can't add right away, at least within 6-12/24 hours (or another reasonable amount) thereby proving commitment (both ways) and loyalty ahead of time.
From the group side, obviously taking into account that some estimated orders might be cancelled (and if they are, buyer should update the order status to cancelled, and include reason (dropdown with reasons like: store cancelled order, decided to keep item for personal use, gave item to another buying group, other).