If I could do it myself, I would have done it already. I have no clue how to alter the python code without corrupting it, I actually had hoped it would be easier. But I already posted the solution to the specific problem I encountered: not being able to add hdmi-in to a quadpip.
Just suppressing the line:
329 if not sref.startswith("1:"):
in the qpip.py didn't do the trick, nor deleting the two lines Dimitriy suggested. As I didn't understand the dependencies I gave up after a while and just edited the "1" into a "8192" so I could add the channel entry to a quadpip. Another way would probably have been to edit the QuadPipChannels.dat directly.
So if someone with a bit more knowledge would just suppress this line and alter the rest accordingly it would be a step in the right direction.
I'm just a bit disappointed that after more than 5 years some of the unique selling points of the VU+ 4K boxes like hdmi-in, quadpip and in this case the combination of both still are far from being well supported.
I am aware that the lack of support from VU+ has left the OpenPli team with an almost impossible task, but every few years I also have to vent my frustration that I can't make full use of the box of my choosing with the image of my choosing (that supposedly supports this box).