Tegan there is a chance they will let DF come back for the birth.
My brother was allowed leave during his basic training from the Army twice. The first time to visit our really sick Grandfather and the second to attend his funeral 2 weeks later.
One issue with that is he either may have to stay back if he misses too much (the Army calls it back-squading) or work his can off when he gets back.
There is further travel involved with your situation than my brothers, though it was still a 4 hour train ride.