Yes and no.
Breast milk is a bodily fluid, so there is the risk that if one girl had something like hiv, she could pass it to another person.
Generally, you'd buy a new "kit" for each girl to use. That would be the hoses, bottles, etc for each girl. So that they don't swap parts. But they can all use the same machine no problem.
You might even be able to use the majority of the same parts, as long as you boil them or what not so they are clean. My mom would know more. I only have "contact knowledge". *laughs*