Would need a LOT more information before I could answer that question.
What is the slope of the two roofs? What kind of shingles?
I presume the BR is an add-on. Slab foundation or post and beam? How is the add-on fastened to the house? Where are you located (climate)? If you are in Florida, the answer gets a lot more complex!
You might want to post this to the Handyman Forum of www.handymanwire.com where there are regulars that have experience in this and where the responses are much easier.