The current plan, which of course is subject to change, is for two additional Q400s to join the Brussels Airlines wet lease from Sept/Oct.
As I understand it those two additional aircraft will operate NCL-BRU and BRS-BRU 3x daily (overnighting at the UK end). The two current aircraft currently overnight in HAJ and BHX but not sure whether that will change in the winter.
I've not heard anything about EDI but perhaps if one of the aircraft will no longer by overnighting in BHX maybe it will overnight in EDI instead (purely speculating now).