Unless you want join me and my friend to/at the concert.

[B45]

Unless you want join me and my friend to/at the concert.

Are both okay?

 

[MikeNewYork]

That is not a sentence and there is no context. That said, "at" is the only possible choice of the two options.

 

[B45]

That is not a sentence and there is no context. That said, "at" is the only possible choice of the two options.

I told my mom that I would like to spend tomorrow with her. And she replies with:

Not sure if I'll have time tomorrow. Unless you want to join me and my friend to/at the concert.

Better?

 

[MikeNewYork]

Yes. It always helps. My answer is the same.-- "at".