Birth Mother expenses????

I'm not sure what the "average" monthly expenses are. It seems to range from nothing to "a lot". We were matched with our emom very early in her pregnancy (13 wks). That meant that we would be paying for 7 months of expenses. Initially she and her husband requested more $, then the attorney decreased it to about $1000/month. That's a big chunck of change as it's for 7 months! Now we are being told that they want to move and are requesting another $200/month. We are so close to the due date (Apr), but it seems like they have tried on numerous occasions to ask for more $. I don't know what to do.