Complex package replication question

Complex to me, anyway.

We've got two DPGs set up. DPG1 contains all of our existing DPs. It has all software assigned to it. A large portion is set as High Priority packages (don't ask... this is a client and something to fix). Many packages appear to still be replicating. DPG2 is new. We're replacing some of the existing DPs with new hardware/Server 2012. We have only the software we feel is mandatory at each site set to replicate to this DPG. New DPs are not part of DPG1 - only DPG2.

We also have bandwidth throttling going on from our Primary Site (where we create all packages) to each other site. We have the DP where we create packages set to 7 outbound connections at a time.

I know that packages replicate according to priority. I also know just one package is sent from the central DP to the branch office DPs when bandwidth throttling is turned on. My question/confusion is when will the new DPs in the new DPG start getting software? Does the replication that needs to complete for the DPs in DPG1 need to happen before the new DPs in DPG2 will get anything pushed to them?

Is there a way to stop the replication of specific packages in DPG1 if they have not completed?