Actually, I just noticed that. I've been translating it is 'can meet smiling' but if it's masu stem + 合う then that changes it a bit, doesn't it? I always overlook those two...
Sorry, I'm a little confused... it's incorrect to to translate it as 'if' here, isn't it? (If you're referring to what I originally thought it was, I saw it as "if we are reborn (meaning that might not happen) then in that life I will not forget you.")
I changed my previous post a bit - "though I wish that we will be reborn and can smile at each other again [if that doesn't happen] I won't forget you" - is that correct?
Or just "I wish that we will be reborn and can smile at each other again someday .... I won't forget you."
I wish that we will be reborn and can smile at each other.
I won't forget you.
There is no relation between the two lines.
(I said また生まれ変わっていつの日か笑い合えたら、君を忘れない can mean "I will forget you unless we will be reborn and can smile at each other", and it's weird.)