You cannot attach a 2015 Form 8606 to your 2016 tax return.  It is never appropriate to do so.

If your 2016 tax return needs to include a Form 8606, it would be a 2016 Form 8606.  Any amount from line 14 of your 2015 Form 8606 would carry forward to line 2 of your 2016 Form 8606, assuming that your 2016 tax return requires that Form 8606 be included.