good for you for adding pics,
but can I ask why are you doing this ?
I have the same as you a wfp and a brush, I use a y piece I can pull this off in less than 2 secs, add another brush simple.
why the need for a rectus 21 fitting and a tap and a male/female connector ?
seems like trying equip to climb a mountain when its only a speed hump

No disrespect but I am baffled ( no pun intended)