How to share an eshop account between two 3DS'?

[trenchdragon]

I want to share the balances on my eshop between my two 3DS'... how do I do this?

 

[Nerd House]

If it is possible to sign into both using the same Nintendo Network ID, then you can do so. Try it?

 

[Boidoh]

It's not possible. When you first create an NNID on the 3DS, it explains how NNIDs cannot be share among two Nintendo 3DS systems.