Adjusting CG's - will it need to do a full init again

RP SE 4.4P1 using vRPA clusters running 2 vRPA VM's at each site, over a MPLS with 100Mb and approx 95ms latency.  SAN's are VNX-5200's at each location.

We have had some business changes, which is affecting our SLA's for a decent chunk (approx 24TB) of data.  Most of that data will be archived off to a cloud resource, and no longer need to be replicated.  When we initially setup our CG's, we had no idea this would be happening 3 years later (crystal ball broken...).  We had built our CG's with Volumes that had LUN's that were similar in nature (this particular CG consists of large VMDK's with mostly unstructured data).

We would like to remove some of the volumes in this CG once we have the data archived off.  The CG is currently replicating 37.5TB of data.  The two volumes we would like to remove are about 28TB of that 37.5TB.  If we remove those volumes from replicating, will a new initialization need to be done on the CG or will it just remove that data from each end?

Our concern is the low BW and high latency on the WAN link, and the time it would take to do a full data sweep.  The last time we made changes to our CG's, it took almost two weeks for everything to sync back up, and that was a bit nerve racking.