[quote name='mickeyp']Can you add two 3DS to the club nintendo and get 80 coins for linking to the eshop or only one? Can you get coins for 2 different 3DS systems-160 each or not?[/QUOTE]
Yes, you can.
This is how family accounts work:
You have one account, which you can turn into a family account. From here, you can create up to seven more accounts within that one family account. All eight accounts will be treated as separate accounts, with the exception that all coins are pooled together within the family. As such, you can buy and register up to eight of any game or system, register them one per account, and have the collected total of all eight registrations available to spend on any of the accounts.
For example, if you were to buy eight copies of Wii Fit Plus and register them all under Group A with registrants a-h, Group A would have a net collective coin balance of (8*50) 400 coins before doing the surveys. All eight registrants would have access to all 400 coins, but each registrant would only have registered his one unique code for the game and subsequently only be able to fill out one Post-Play Survey; all eight accounts would have one Post-Play Survey each, giving another 80 coins. They are all treated in the database as individual accounts, which are linked through a primary key to the group account, allowing them to share coins.