Hacking Question about DSI Downgrade

[Lumince]

So my friend wants me to downgrade his 3ds using my A9LH New3DS but Id rather not transfer my NNID and such to his 3ds. So I was wondering if something like this would work even though its inconvenient to do this.

Idea 1:
If I create an Emunand on my 3ds, unlink the nnid and restore my sysnand from a backup using this- https://gbatemp.net/threads/how-to-unlink-nands-keeping-original-sysnand.390981/, Then transfer everything from his 3DS to mine after he has installed steelhax and fieldrunners. To my understanding, this should leave my sysnand in tack with his NNID on my emunand with all of his saves, games, ect. From here I would set up the downgrade expolit and then wait the 7 days. After the 7 days, I would transfer it back with the modded fieldrunners and finish the rest of the process. He might not like being without his 3ds for 7 days, but thats better than me and him losing our setups.

Idea 2: Tell Nintendo to unlink his nnid from his 3ds, make an emunand thats unlinked with the same method from the link above, and then link it to my new unlinked Emunand. Then proceed to get fieldrunners and steelhax installed. Of course we would backup his saves, and redownload the games he has onto mine before transfering it back to his 3ds. He has everything and I have everything.

Im gonna make sure that I make backups of both sd cards and my sysnand before trying these :|
If they are stupid ideas, then Ill just go with the original plan,

 

[Quantumcat]

You probably won't be able to transfer from his console to your emuNAND if your NNID is still linked to your sysNAND (it will look to the Nintendo servers like you're trying to transfer to a console with an active NNID). For this part you can probably a) make backup of sysNAND b) format sysNAND to remove the active NNID c) do the transfer d) restore backup to sysNAND (won't be able to use NNID services on your sysNAND) then e) do the DSiWare hax thing then f) transfer back then g) should be able to sign back in again
UNLESS all NNIDs associated with a console move with transfer (which is what I think happens) rather than just the active one. In which case your NNID will go with his. But you can call Nintendo to get it relinked to yours, then you'd be able to sign in properly again.

 

[Lumince]

Then it seems like this will be a big pain anyways... Id rather just hardmod his 3ds myself instead tbh....

 

[Cuphat]

All NNIDs move with a transfer, it seems. It's not a huge deal to lose your NNID association for a bit, and you should be able to fix it by contacting Nintendo. Annoying, I know.