This is impossible without the male-to-male connector. Note, also, the female-to-female connector that joins the loop to the main line—freedom from abandoning your plans because the parts don't fit!
The improved versatility of the system really makes me wonder why Brio didn't ship these adaptors with the set we bought!
Accept constraints and focus on essentials. (Speaking on photography, but with wide implication.)
—Mahesh Venkitachalam