I might be misunderstanding what you're asking, but I'll share how I think it works. I'm hesitant to even try to answer since I've been pouring over your "Math Behind" thread the past couple days to try and understand all the info that YOU have provided!
Anyway, here goes: If you're using a constant voltage driver that has a max current output of 5.2A and is set to output a constant 36V, as you connect each COB in parallel, the voltage across each of them will remain constant at 36V and the driver will supply each COB with however much current that it requires, which is determined by that particular chip's unique I-V curve.
At 36V, one COB might pull 2 amps, and another in parallel beside it might pull 2.1 amps. In this case, the driver is operating in CV mode and supplying 4.1 Amps to the 2 COBs with 36V across each. If you add another of the same COBs and it pulls another ~2 Amps, you have now exceeded the rated current output of the driver, and it will hold its max current steady and split it among the 3 COBs.
As the COBs are now getting less current because they're splitting the max amount the driver can output, their forward voltage will drop and the driver will lower its voltage level to compensate, while holding current at max. You can see this in the driver data sheet on the page near the bottom where it shows a graph of the voltage and current output relationship.
A constant current driver will operate in this manner right from startup, and will automatically vary the output voltage required to push its rated current through the circuit.