Dear OC:
Note that DAMBRK will model it as a single system. Therefore, you need to define the desired model flow at the upstream reservoir, and then the routing will take that inflow all of the way downstream.
You can try increasing your base flow for the upstream reservoir inflow hydrograph, and then to route that larger base flow into the next downstream reservoir, specify this larger flow for the "Turbine (or Other)" discharge value for the upstream reservoir.
I don't think that you need to worry about a minimum channel distance between the reservoirs. You can specify as short a distance as you want.
Sincerely,
Chris E. Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com