You can follow the instructions mentioned in the below link to edit the settings for your My cloud device to perform a Remote backup. However, In order to configure settings for your other NAS device to accept the remote backup you would need to contact the original device manufacturer:
Thank you for reply.
Unfortunately, that looks very complicated for me. I was hoping that I will setup this in a while, using your cloud service. I will look for some alternative setup that will fit my needs.
Officially, the ability to backup from one My Cloud to another will depend on the My Cloud model and the firmware it is running. Currently the second generation single bay My Cloud units running V2.x firmware DO NOT support being a backup target for another My Cloud. See the following WD Knowledgebase article that indicates which My Cloud units support being a backup target for another My Cloud device.
Unofficially it may be possible to use SSH to issue a Rsync command to copy data from one My Cloud to another. Or it may be possible to use FTP which is insecure to copy data from one My Cloud to another. Another potential unofficial option is using GoodSync.