Merge GroupWise into new primary eDirectory tree

Hi,
I have worked on an installation, where we decided to install a brand new tree on new oes11sp1 servers. File, print and other services are fine.
For the migration period, we left the GroupWise server alone in the old tree. I have migrated it from NetWare gw8 to oes11sp1 with GroupWise 2012, but still in the old tree - which I want to get rid off.
Current GW server use NSS for storage of post office and domain, with drives mounted into old eDirectory tree.

Current GW server is a virtual guest, sles11sp2 OS. So my target is to get GroupWise crafted into new tree and old tree completely removed. How can this be done safely?
Will it be safe to simply:
- Stop GW daemons
- remove eDirectory old tree from GW server and with that stopping nss, which handles GW volumes
- reinstall eDirectory on GW server into new, existing tree (running on other servers)
- mount old nss volumes into new tree. How is that done?
- start GW daemons again
- craft GW objects into new tree matching GW users with eDirectory users in new tree

Any thoughts, ideas or recommendations?