By all means let her tease him and have stupid arguments with her big bro. They can have a sass-off.
A cute nickname related to art perhaps or maybe the more traditional affectionate "Nattie?" The perfect bribe. Great distraction tool.

I shall inform the Draco player of our plans!
I was just talking about how Foggy might have gotten his nickname in this AU and someone suggested that it could have been a mispronunciation of "Franky" via a younger sibling when they were a toddler and it stuck. Would you like to give the honors to Natalie?

Natalie Nelson. Stan Lee would be so proud of the alliterative name usage!

Yes! I know exactly what you're talking about. Love Orphan Black!