I loled, especially with the blondes.
To the question above, it really depends and cannot be answered a priori. There is an optimal amount of the labor force relative to the current stock of capital and land at all times. Increasing population may increase MPP schedules and make workers more productive (an example would be because of the division of labor, Crusoe is alone on an island and suddenly Jack and Bob are wrecked ashore. With the greater supply of humans below the optimum point, they can do more things together, specialize, and become more productive). But beyond the optimum point the population becomes burdensome. If 50 more people were to land on the island and with the current capital stock there wasn’t enough tools/food/land for them to use, them being idle and leeching off the others would certainly decrease overall labor productivity.