The model has to be pre-defined when a simulation is created.
Please specify the nature  of sticking force. Is it a constant or is it depends on number of particles sticked together? or...

You only said when blue particles touch , they should stick together; when green particles touch, they should collide with each other.
What will happened if blue particle touch green particle??? Ignore?

What need to be conserved when blue particles stick together? momentum and angular momentum?

What is the purpose for the simulation?