I use a Campy NR front derailleur on a couple of my bikes with Spécialités TA triple cranks. They work fine with a granny and half-step chainrings. My practice has been to get the granny gear close to the chainstay. The chain line at that point with 6 and 7 speed cogs has never given me any issues.

And for what it is worth, I have added a dent to the chainstays on a couple bikes to make sure the TA granny clears them.