If you just read someones elses QR code with the machine, no you can not edit it. There's a way around this though. The qr tool thats been posted here a few times.(Its called Uber animal crossing qr tool) can get around this. First you make a QR code of your own with the abel sisters machine, save it to the 3ds and then you open that qr code with the tool/app on your computer. It'll read you your town name, author name and a special ID which dictates who's pattern it is. Save all the info as default and then load up any image you want, create a qr code that you can then read with the machine in abel sister shop and bam, the game considers it your own design and it lets you edit it. Ofcourse don't plagiarize some elses work with this!