Hi Eduard,
Is it possible to add L-System simulated for "Path position distributor", "Path position distributor" just a very simple parallel rewriting system now, it can just add one rule at the same positions, just like below ( Branch is defined as "A"):
You will see "Path position distributor" can just simulated itself, it flow the rule A→AA
But we can custom lots of rules with L-System. You can reference these links below:
https://en.wikipedia.org/wiki/L-system
http://algorithmicbotany.org/papers/#abop
This function will offer more customizable for GrowFX