Evening,
There is no reason why you cannot do this.
I do it to a remote NAS on another WHS,. This WHs backs it's folders up to a NAS on my Network. Also, I sync all my shared folders from my OEM WHS to an RC WHS server. Reading various posts through the forums, there are numerous people doing this, one way or another. There, as yet, isn't anything built in to WHS to accomplish this, but there are 3rd party applications - RoboCopy - SyncToy - SecondCopy, plus, I guess, others that can be used to do this. It really depends on what you feel comfortable with and whether you want to use Free or Paid-for software.
Colin