Odd Brake Issue

[CapeX5]

Hello All,
05 4.4. Just had 2 rear brake lines that rusted out and I replaced them. Car was operating perfectly before rusted out lines. There was a delay in getting parts and the reservoir leaked all the fluid out. I filled, did a Motiv pressure bleed. Was getting minimal fluid out of rear caliper bleeders. Hooked up my Foxwell and found the brake bleed procedure. Did this numerous times on all wheels. Fronts had plenty of fluid coming out, rears had minimal, with some air. Still not getting brake pressure to the rears. Started disconnecting lines at the ABS module and front circuit was flowing fine, rear very slowly. Figured I messed up the master cylinder. Replaced it. Same situation with fluid flow/quantity to the rears. Took old master apart and realize that the rears won't bleed with pressure in the front brake circuit of the master. I decided to have someone put pressure on the brake pedal, bleed fronts, than with pedal still down, open the rear bleeders and get air and plenty of fluid out. Almost like all 4 need to be bled simultaneously. I have searched everywhere and plenty of posts on the rear brakes being a problem, but no solutions. Now, I can't access the ABS module on my Foxwell and the pedal is super hard. Took for a test drive and the brakes started to seize up and I had to release the pressure at the ABS module where the 4 lines come out of the top to each wheel to release the calipers. I do have INPA and tried to access the ABS/DSC module but could not find it.
I am so sick of this car and how complicated it is. I would appreciate any help or suggestions sorry for the length of this but thought all information was pertinent.