Hi ChelsB. TFA Blueberry Wild is very tasty, but it's not very strong. You'll have to add it at 6% or more if you hope to taste any of it in the mix. I'm not too sure, but I think Wizard Labs resells the Strawberry Lemonade flavoring from Flavor West; I'm not familiar with that one, but the notes on ELR peg it as not very strong either. If you want the blueberry as accent, maybe try 9% SL + 6% BW. I think that's how I'd do it.
Please let us know what you try, and how it works!