Thanks for the feedback.

"We're going to need a bigger boat" unfortunately both hosts are fairly utilized and host A cannot take on the load of host b even temporarily.
If what you say is the case my only option would be to add a new empty host (host C) to the pool, add the shared storage to the pool of two, migrate VM's from host B to new host C so all VM's are vacated from it and lastly add host B to the pool.

I have (2) XCP-NG 8.0 servers each running in their own pool (standalone). I would like to non-destructively add the second server into the pool of the first. Each host currently has a local SR with active VM's. I am implementing a new ISCSI SAN and need to get these hosts put in a single pool. I see where to do this in Xen Orchestra but just wanted to confirm before attempting this.

I have read some information that says adding or removing a host to/from a pool will "reset" the host back to a fresh install state and wipe all VM's from the host. I would like to confirm if this is still true on 8.0 or if that was the case on an older version.

My goal is to have a couple of VM's stay running on the existing local SR while selectively migrating VM's to the ISCSI SR. I am not ready to move all to shared storage at this time. I am aware of the impact that has for HA and this limitation, it is only temporary.

If someone can confirm the functionality it would be appreciated. Is it a best practice to shutdown the VM's on the host before joining it to another pool? I do plan to have full backups in place before attempting this move.
Will removing a host from a pool destroy any VM's running off the local SR?

Any feedback is appreciated.