first off just wanted to say thank you all for your replies they are very much appreciated
thanks for putting my mind at ease , as this is my first time flying with a few connections
and numerous emails to BMI have gone unanswered
edit*****
just got this from bmi
We have the following response from our res team
Baggage will be checked through, but passengers will have to clear with customs on arrival in MIA.
Hope that helps.
Kind regards
Bmi social team
confused does this mean that when we get off the plane at miami, we will have exit the secure zone, and then walk back to the check in desk (as if we were checking in for the first time?)