With vRanger 5.4 you can now use one VA for the entire cluster.
Within each target VA's scratch disk there are directories (with vzmap files) for each VM that is replicated. To use only one VA you will need to consolidate the contents of the scratch disk onto one VA.
Make sure no replications are running when consolidating the VA's.
Run an existing replication task of a VM that used a retired VA. Watch the task details. No rehashing should occur if the VA's were consolidated properly.
Note: The source VA's do not store vzmap files. Since there is no vzmap files on the source you do not need to consolidate the scratch disks on the source cluster. Repeat steps 5-7 on the source cluster.