Hello, I don't think this is common knowledge, but I've just found out what written in the thread title: when you do a system transfer, all NNIDs linked to the source 3DS console are transfered (on the Nintendo servers) to the target console, not just the NNID active in that moment. Here is what I did: 1) On 3DS#1 I had 2 NNIDs: A, B 2) On 3DS#2 I had 1 NNID: C 3) I transfered NNID C from #2 to #1. Then, I formatted 3DS#1 again and linked NNID: B 4) One week later, I transfered NNIB(B) from #1 to #2 Now I've senn that on 3DS#1 I can't link the NNID A, nor B (obviously), nor C. But on 3DS#2 I can ACTUALLY link NNID(C) which I had NOT transfered back. Just to let you know. And I think that Plailect guide should be updated with this evidence. Bye P.S. The steps described above were done for the downgrading of 3DS#2 on 11.0: 1) 3DS#1 was already A9LHed. On it I had NNID A. 2) 3DS#2 was the one to be downgraded with NNID C. I transfered it to 3DS#1 to be sure that, if something went bricking, my NNID would be safe. 3) On 3DS#1 I created NNID B and downloaded Fieldrunners. 4) Then I transfered NNID(B) from #1 to #2 to downgrade 3DS#2 (and I installed A9LH successfully). 5) Then I wanted to transfer back NNID(C) from #1 to #2 but I found out what I wrote.