DDBoost settings change: Single database to RAC environment (Linux)

If anybody has experience of changing DDBoost settings (Linux) from Oracle single database to RAC, please share your experience to us.

A customer is using Data Domain for their Oracle database backup (RAC environment) through RMAN. However, they realized they installed DDBoost in the RAC nodes as single database. Therefore, when they changed their backup node(server) to one of the other RAC nodes, past backup data suddenly disappeared in RMAN...

Now the customer is planing to fix the issue/settings. P.163 & P85-87 of Installation and Administration Guide seems to explain how to correctly setup DDBoost in RAC environment but it is for a clean install and also a bit vague...

We are looking for somebody who have an answer/answers of below two questions.

1. How can we delete orphaned data remaining in the Data Domain? We cannot delete it since RMAN does not recognize it anymore...
2. How to change the current DDBoost (Linux) settings for single database to for RAC database?

It seems we have to change two things below. Are these enough to change the settings?

1. • Set the cluster SCAN hostname for the CLIENT parameter
   • Allow all the RAC nodes to access to lockbox in which DD's credential information exists

When we check the Administration Guide, it says we should use "uname -n" output for all nodes to grant lockbox access (by "ddbmadmin -G" command). Don't we have to use SCAN host name or virtual host name for it instead of "uname -n" output?

Any information is very welcome!

Thank you,