I modified the grbl 1.1h for command 2 unipolar steppers 28byj-48 ... project here costycnc-costycnc-grbl-1.1-unipolar/grbl_costycnc_1.1_unipolar at master · costycnc/costycnc-costycnc-grbl-1.1-unipolar · GitHub
i make free some pins ... because for unipolar need 8 pins ... but i observed that machine entry in hold state self ... i use arduino with new bootloader at 115200 bauds ... the arduino with old bootloader at 57600 not entry in hold mode self ... or not make attention ... can be problem that modify firmware or can be problem of arduino self? thank in advance for a eventually response! good day!
These are nice foamcutters you built 
Before I look into the code, are there some documentation of your changes somewhere?
Thanks for your response ... all modifications is in folder "de schimbat"
Anyway I think I found it the problem ...
A0 (Reset), A1 (Hold) and A2 (Start / Resume) pins ... and i inactivated subrutine that read this pins ... because motor use A0-A3 pins ... and I think they were in conflict...
If you want see ... look in readme file.
So ... seem that problem is solved!