How do you want to mix the colors? If you just calculate an average between the two colors, eventually all children will be grey. Try asking ChatGPT, maybe it will give you some ideas.
But you have lots of other serious problems with your code:
1. You can't check if Blockers has LOS to Blockers and overlapping Blockers. There is no way to distinguish instances and it won't work correctly.
2. Never use "trigger once" with multiple instances!
3. Never use "wait" in events which can run on every tick.
4. Don't put triggers (like "On created") in sub-events.
Here is how you properly do this:
dropbox.com/scl/fi/o41cpviriwnukb43jteaz/BlockersDemo.c3p