That helps. I'm going to use symbols to try to explain it plus that helps me keep my thoughts straight. Capital "O" is the genetic symbol for the dominant blue egg gene. Small "o" is the recessive not-blue gene.
Their father, the Marans, is o,o, no blue egg gene. Since the mother laid an olive egg and one of the pullets lays a brown egg, the mother was O,o, only one blue egg gene.
That means the pullet laying the brown egg is o,o, no blue egg gene. The rooster and the other pullet could also both be o,o, maybe both are O,o, or maybe one is O,o and the other o,o.
If he is o,o and you cross him with the brown egg laying pullet you get brown eggs. If he is O,o and you cross him with that brown egg laying pullet about half the eggs should be brown and half green.
If the other pullet lays a brown egg she is o,o and you get the same thing depending on what he has.
If the other pullet lays a green egg she is O,o and he is o,o you get half and half. If the rooster is O,o then a cross with the green egg laying pullet should get you 3/4 green eggs and 1/4 brown eggs.
So what does all this mean? If that second pullet lays a green egg and you hatch enough eggs you will get some green egg-laying pullets no matter what rooster you use. If her eggs are brown you might or might not get any green egg layers from crossing her to that rooster.