I have thise setup, although I push all pos sales to booking system so that system has full complete total sales for both.
Out breakfast is 0 priced as all rooms are b&b
I then have samba know if room is dinner Inc and if so use a dbb price list where most is 0 and supplement items like steak have supplement price.
This then gets charged to guest bill in PMS as 1x item [Package] £0 or supplement price.