So I currently have a surface outpost on both Mun and Minmus, but I've now received two more contracts to do the same thing -- one outpost on each moon. Instead of creating a whole new outpost, is it possible to extend the existing base, so that the total requirements of the new contract are met, without making a whole second outpost such that it would complete the contract? It says that it must be a new outpost build for the agency after the contract is accepted, but I know once you join vessels together (I have docking ports available) it makes one large vessel (until you undock them again of course).
You will be able to get it right if the old base attaches to the new module, and not vice versa.
In order to do so, right click a command module or probe core; on the existing base - pick the icon of probe or lander or rover. On the new module, pick the icon of base or space station.
That way, when you dock them together, the game considers the new module to be the "base" (which is new, produced after the contract) and the base a "module" added to the new "base".