I HAve an mth R 17 and i was wondering if a proto coupler can be added to the front since it has a manual coupler can u swap it

If it's PS2.0, yes, but it should have one already. If it's LocoSound, no.

yes put does it have a second port for that coupler and is it hard to change

On the PS2.0 harness connector with 12 pins, the purple wire in the #2 spot is the ground for both couplers. The black wire in the #9 spot is positive for the front coupler and the brown wire in the #8 spot is positive for the rear coupler. I'm not 100% sure the subway soundset supports front and rear couplers. Someone else would have to verify this.
Swapping out a coupler is only a matter of popping off an e-clip. Just make sure you watch where it lands.

yea the sound has a front coupler because when you hit the front coupler button on the dcs u hear the sounds play but no coupler opens cuz there isent one there