If I am reading the Senate bill correctly, for Mil-to-Mil this is even worse than last year's attempted BAH change (only get BAH for highest ranking member). With this change, a Mil-to-Mil couple with dependents would not even get the highest ranking BAH because the new formula would be:
Member BAH = Max BAH/Number of members in household
For example, lets take two O-4s living in DC with kids, Member 1 would be entitled to BAH w/ dependents, Member 2 w/o dependents.
Member 1 BAH = 3108/2 = $1554
Member 2 BAH = 2673/2 = $1337
Total Mil-to-Mil BAH = 1554 + 1337 = $2891
So, an O-4 married to anyone except another military member living in DC would get a max BAH of $3108, but a Mil-to-Mil couple with dependents would max out at $2891. This is on top of the same couple also taking a ~$30K/yr pay cut from what they would be entitled to under the current rules.