Kemsus on 15 February 2015
if you can play MM on the N3ds xl without creating a NNID you should be able to transfer that to your n3ds first, if that is possible then MM is tied to the N3DS without an NNID yet, then you transfer your Old 3DS XL to your N3DS with your current NNID and now the MM game should be associated to your NNID.
this is how it worked for me with 2 systems, but i dont know if you can do it with 3.
also there is a 7 day lockout period on doing system transfers.
