Nick & Dave -
The tweak is up there now. The total balance will be updated for the direct parent customer on the subsequent changes-only sync, so you are now looking at a 20 minute delay instead of full sync every morning.
The problem stems from a limitation (bug?) in the QuickBooks SDK. The parent customer is not flagged as having been modified, even though the total balance changed. In QuickBooks 2008 they fixed this issue somewhat, by finally flagging the base customer as having been modified if they had a transaction pass through involving them. But they never extended this tweak up the Customer:Job hierarchy. We query QuickBooks for any customer that has changed since last time we did a changes-only sync, and since the parent customer hasn't changed, it doesn't get picked up by the query. The tweak I made was that if a customer has a balance change, and they are a sub customer, then flag its parent as needing to be updated on the next sync.
Paul