Hi Dragan,
Unfortunately i don't see a way to implement this in the current workflow.
Generators are evaluated separately, with the only exception of parent-child relation (nesting, basically).
To interchange values between generators, it would be necessary to set an extra hierarchy, to define the evaluation order.
For example, if Gen1 uses SplineLenght of Gen2, Gen2 must be built before. That complicates a lot the current implementation, and may introduce other potential problems.