I'm not sure it's IP addresses as much as DECA nodes.
Having a couple of DVRs & a receiver, doing a system reset has changed the DVR order.
From a bit of playing around with DECA nodes, it seems one node will be the master. If this stays online, all the other nodes can be rebooted and come back with the same order [node number].
So, when you reset your DVRs and receivers, the DVR order (as seen on the Whole Home Status page: Menu, Whole Home, Status) reverts back to a particular order, or DVR on top of the list?
On my system, the order in which DVRs and receivers are powered up first (while others are powered down) will determine the order of my DVRs.
I'm running MRV via ethernet (with exception of HR34 and H25, which are connected by two separate WCCKs) so perhaps that has something to do with it and why I had deducted that acquisition was based on which IP address was found first (which are static, by the way).