Enlistment procedures currently require waivers/reviews for the number of dependents as well as dual military (to verify that they can be stationed together). We even forbid single parents from enlistment due to the military being demanding of time/energy.
Consider 2 E-3's stationed in California who get married, move out of the barracks, and have a child.
They pay for housing with the first BAH, then collect the second as a %100-200 pay increase (factoring TiS, location, etc). When one deploys, the second becomes a single parent- which we actively screen out in the first place. What we effectively do with this dual-BAH system is offering financial incentives for young service members to reduce their usefulness to the military.
I suggest grandfathering those who got married with the current incentive package, reinstating sole BAH for the senior member for all subsequent dual military couples, and looking at the 'zero dependents bonuses' as suggested earlier.
I'm not anti-family, and my wife has been spectacular through deployments/training, but family issues require time, and exponentially so when dual-military. A single junior Marine is more useful to me than one who can't work late and will statistically end up divorced.