user can add and remove BA and/or Loc from the matrix to fine tune quote

user can select multiple BAs but only one Location at a time when adding to the quote. The UI should allow the user to deselect one or more of the BA/Loc combinations.

for example, user initially selects/adds BA1, BA2, Loc 1. This produces BA1/Loc1, BA2/Loc1 campaigns.

subsequently, user can add BA3, Loc2. This adds only BA3/Loc2 campaign. it does not create the following cross product:

BA1/Loc1, BA1/Loc2, BA2/Loc1, BA2/Loc2, BA3/Loc1, BA3/Loc2.