Can I have priority passed back to me during spell resolution, so that I can do more with my own spell?
If you wait for your opponent to respond and your opponent has no response, your lightning bolt resolves before you can twincast it.


  608.1. Each time all players pass in succession, the spell or ability on top of the stack resolves. (See rule 609, “Effects.”)


You'll only get a chance to copy the bolt if they respond, or if you cast both spells before passing priority the first time.