Resistors in N-Way Wilkinson Power Combiner

How are the values of the isolation resistors in a 12 W Wilkinson power combiner determined? I know that for the 2 Way the value of 2Zo comes from matching the common port to the output ports. But my 12 Way design which uses 4 sections will use different resistors at different steps in the cascade as it is a stepped Wilkinson design.

Evelyn