For clarity, assuming you're asking about swapping out your ISY994i for an EISY, and how to swap them in HA as easy as possible. After some tinkering, i was delighted to learn this was pretty easy, and I didnt need to set everything up in HA again.
1. assuming you've already replaced your ISY994i with EISY using the ISY configuration consol and backup method, and it's configured (talking to your PLM and controlling things)
2. do a full backup of your HA configuration (just in case)
3. Delete your Universal Devices integration in HA
4. Make sure the devices and entities are gone. You cards should all have yellow errors where the devices used to be.
5. Perform 'add integration' for Universal Devices.
6. Once executed, HA shoudl see all the devices again, assuming they are all the same names and IDs
I just did this and was suprised this wasn't on this forum.