Just a couple of thoughts....
1) If there are numerous Canadian members interested, would it be cheaper (postage wise) for them to have their own robin? I don't want this to sound like I am excluding anyone...please, no offense meant, just thinking of the $$$ aspect.
2) When I last did a row robin, the rules stated only the width of the row, nothing else. (We had 6 members in our group). We each made a row, and enclosed some of our favorite fabric that we had used in our row, and a brief note about why we chose that particular theme (block, colors, etc.). Each person could add a piece of fabric to be used and added to the note. When we got our tops back, we had 6 coordinated rows along with their "story".
Whatever is decided, robins are a lot of fun to participate in. Thank you to QuilterMomma and Mariposa for helping to get this started. Not sure if I will join yet, but will watch this thread closely.