What about the boardinghouse rules make it hard for Lyddie to have Rachel with her?

Lyddie is a factory girl who works for a corporation. She also stays in a corporation-owned boardinghouse. What all this means is that Lyddie has to adhere to certain rules and social protocols. Earlier in the book, readers learn that Lyddie has to buy new clothes when she first arrives because it just won't do to look like a dirty farm girl. Additionally, Lyddie must attend church.
In chapter 15, Lyddie is reminded of another of the boardinghouse's rules. The women are not allowed to have any men or children at the house with them. This is a problem for Lyddie because her Uncle Judah has just brought Lyddie her sister, Rachel. Lyddie's mother is incapable of caring for Rachel, and Uncle Judah can't do it either. Uncle Judah expects Lyddie to care for Rachel, and that puts Lyddie in a bind. Rachel isn't allowed to stay at the boardinghouse because Lyddie isn't allowed to have children there, and Rachel isn't old enough or strong enough to be a factory employee.