Pay bills and record offline payments in Bill.com. The sync will push the payments into Sage Intacct.
Void payments in Bill.com. If you've also deleted the bill in Bill.com, manually reverse the bill in Sage Intacct.
Since the sync can't reverse a bill in Sage Intacct, you may get a sync error for the bill. Click Fix next to the sync error, and then click Next. The sync error will clear.