I did one time such thing. But I had only one child, who, practically grew in the library near me. But it means no weekends at all (library), not enough sleep at night (cooking for next day, washing, etc). Here your friend will need a lot of support and help from her husband. Unfortunately, I didn't get it, but may be she can be lucky one. Also parents can help. I didn't live with my parents, they were in another town, but I think they can help with kids.
But the most important will be her will to do it.
Good Luck!