How to move cameras to new system?

Hi, I have just bought an extra Sync Module 2 (came with new outdoor camera) for Amazon.

I have installed the Sync Module 2 as a new system called ‘Indoors’ so I now have 'Indoors’and ‘Outdoors’.

I would like to move 2 existing cameras to the new system. Reading help in the forum I deleted the first camera from existing system and then went to add it to the new, but I get the error:

‘Mini Serial already registered to this account.’

Is there a way to move cameras from one system to another using the App?