Done this mod to my own car so decided to write up a guide
Retrofit rear electric windows, this was done on my 2014 Fiesta Titanium but I believe should be the same for all facelift mk7.5's
Drivers door window switch for all windows
Door cards for both rear doors with electric window switches
Inner door panels for both rear doors including motor/regulator and door control modules
Wiring looms for rear doors (most inner panels if buying from a breakers will include the looms)
Access to forscan to make a programming change
An extra pair of hands will make this much easier
First we need to remove old parts
Rear door cards need to be removed, if you follow the first 4 pictures you will see we have 3 bolts to remove, 2 behind/below the big black handle in the middle and 1 behind a small cover in the door handle. We also need to remove the window winder, this is held in by a small clip which can be pushed/pryed off with a little patience. Last bit to remove is the small triangle piece, this is held on by 1 clip and using a prying tool can be pulled straight off (Pic 5). Now remove the door card and once removed unclip the door handle mechanism behind the door handle.
This will leave you with picture 6, the inner door panel.
Now before going any further we need to make sure we get the next bit right to make is easier for us. Basically all in one go we need to remove the old inner panel and replace with the new so we want to make sure no mistakes are made as we are disconnecting the window. Make sure your new inner panel is close and ready to be fit. In the picture you will see 2 green circles, remove these covers to expose the 2 bolts holding the window, you may need to use the winder to move the window up/down so these are exposed. Also check the new panels line up and screws can be accessed. Now we need to disconnect the electrical connector marked in blue and then with the help of a friend you need to loosen both the bolts holding the window then remove all bolts I have marked with red circles. At this point with some wiggling the window should come loose from the panel and the panel can be removed. Your friend will need to keep hold of the window you don't want it dropping/breaking, this prob could be done on your own by wedging the window but I would not recommend it.
Put the new panel in, put a couple bolts in to hold while you drop in and line up the window. What I recommend doing is at this point to not do up the window bolts fully only enough to hold lightly and only put in and do up the panel bolts. Reason for this is we want the window to sit properly and the best way to do this is to hook up the electrics and close the window fully then do up the bolts fully.
Repeat this full process on the other rear window.
Now we change the drivers window switch. pictures 8, 9, 10 and 11
Firstly remove the black trim, this prys off and pulls forward towards the front of the car to be removed, you can see in picture 8 the little piece you pull forwards for. Pull out the plastic cup from underneath revealing the 2 bolts, remove the bolts and the whole switch unit will come out, unplug the electrical connector from underneath and replace with your new switch unit and put back together reversing these steps.
Not too much left to do now 😄
Hook up forscan and change central config, can't remember of the top of my head exactly what settings its called (I will get a screenshot at some point), look for windows and change from front electric windows to full/all electric windows and save the change to the car.
Now at this point we want to connect switches to the rear doors to operate the rear windows closing them to seat them then opening and lining up to tighten the bolts OR if you have a friend get them to operate the rear windows from the front switches while you look to line up.
Close windows fully then open them up to the point you can see the bolts holding the window in place - Now tighten these bolts up fully holding the windows.
Make sure all bolts are tight, connect the inner panel loom to the switch on the door card not forgetting to reconnect the door handle and fit door cards simply the reverse process of removing.
You now have full electric windows 😉
I have added extra couple photos showing electric window inner panel fitted and also the wiring looms needed as these seem harder to find