Multiply, in generic terms

I wonder if “Be fruitful and increase in number” (Gen 1:28) is meant as an command to individual persons or to humankind as a whole. I would rather say, to humankind as a whole, because God adds, in typical Judaic parallelism, the same content verbalized as: “fill the earth and subdue it” (Gen 1:28).

So it seems the command is not for everybody to have children, but for humankind to fill the Earth. And there are plenty of tasks to do that are not about having children oneself, and that contribute to humankind filling and ruling (in a positive way) the Earth: caring for orphans, caring for children medically (so that they do not die), caring for adults medically and mentally (so that they can have and educate healthy children) etc..