I want to add a second WD PR4100 - Help?

I have a 32TB WD Pr4100 NAS that is dedicated as my Plex server and storage. I am down to less than 1TB of storage remaining and have purchased a second WD PR4100. I would like to use this second unit as media storage only and would like to extend my existing libraries to the second unit. I do not want to set up a second server. I have no real networking experience but am not afraid of this either. I would appreciate if someone would be willing to guide me through this setup and maybe recommend best settings and practices.
The WD4100 has worked flawlessly for over a year and play both 1080 and 4K movies without any issues to our Apple TV throughout the house.
Let me know if I need to provide more detail or how best to move forward.

Thanks

@wniels - It should be easy as setting up/sharing your ‘new’ PR4100 folders with a samba (often listed as CIFS or ‘Windows’) share within the new NAS.
Basically, get the new NAS up and running, name it, set shares \\NewNAS\Movies, \\NewNAS\TV, \\NewNAS\Music ... , set up same user:group that plex runs under on old NAS to have same permissions on NewNAS shares, then go into your PMS server on old NAS and add additional folders to any of the libraries.
Example - you have old server, it has file structure \\oldnas\Movies in it’s Plex Movies library.
Edit the Plex Movies library to also point to \\NewNAS\Movies in addition. Now that it’s pointing to both locations, you can move a file there or put new ones.
*Though in same library, a move may still show up as ‘new’ - I forget - try a single move before moving many from old to new if it’s play history and stats are valuable to you.

@JamminR - Thanks for the info… i think I understand and will work on this tonight and let you know my results. Your time is appreciated.

@wniels - sorry so late with this, but there’s valuable information in the KB articles if you want it to keep metadata.
https://support.plex.tv/articles/201154537-move-media-content-to-a-new-location/
It includes some of the steps I generally mention, but may allow for keeping the play stats/etc.

If you just start adding new files, no big deal. Plex will pick up like always.
But if you decide to move some media from old to new, then there are some good steps to follow.