Thanks 
But, could you really assist with the second question?
Given the fact that all the (smallest) agents can path in the same way that the biggest agent can path
it looks very natural that a tweak could be done like - make all the bached detour querries to happen on the NavMesh with the biggest agent - while send a pathfinding/pathfolowwing orders of agents to their respective NavMesh.
The main question is: how would I accomplish it in a best way 
I mean- it is 100% doable, but to figire it out alone can take a year, however with a littlw assist from some1 who knows exactly what is going on it can be acomplished in a hour