I wonder if Silver/Gold *A passengers will get lounge access at BRS if flying on a LH issued/coded ticket?
Sadly not. *A rules mean it's the
Operating Carrier who qualifies lounge access, and BM aren't (yet) a *A member. That means no lounge access, in BRS, FRA or MUC. (Unless LH*G arriving long haul on a flight numbered LH400-499)
You won't earn any miles in any *A mileage scheme for the BRS-FRA/MUC segments either.