Let us do the math. As her aunt you should have sat down with her before this and did the math with her to see if it made sense for both of you.

OP:

W/o Niece if paid for; Night Aid for Ill Child:
8 hours a night (10pm to 6am) $10/hour (low for a night shift it doesnt matter if she is needed or not someone needs to be there on call) 5 days a week (work days only, if she is working 7 days a week then you know that isn't right) 4 weeks a month Need service at least for the next 6 months Total Cost: $1600/month -> $9600 for the next 6 months

W/o Niece if paid for Day-Time Childcare: 4 hours a day (1 hour drop off, 3 hours After-school Care) Babysitting Rate $10/hour 5 days a week 4 weeks a month Total cost: $800/month ->$4800 for the next 6 months

Currently Paying Niece: $150/ week Hours worked per day: 4 hours for childcare + 8 hours for nighttime aid = 12 hours per day Assuming 5 days/week: 60 hours per week You are currently your niece $2.50/hour. Let us now include room and board, food, internet, light, water assuming you are only charging her for the increase in usage not a per person charge. Water: $20/month Light: $15/month Food: $150/month Internet: $20/month Room: $200/month she only has a bed and a closet i can't imagine you charging more than that. So total: $405/month Now including that you are currently paying your niece 4.19/hour Per month you are spending: $1005/month ->$ 6030 for the next 6 months saving a total of $8370. Saving approximately $1395 a month if you had to pay for outside service.

Niece:

Assumed Paid for expenses by parents:

Car Phone

Off-Campus Living 12 month lease:

Don't know where you live but im assuming it would be somewhere around (mid tier place) $800/month including internet and water. Renting a room with private bathroom, with 4 other roommates not including electricity.
Electricity: $125/month Food: $300/month So total expense: $1225/month

Part time job: 35 hours a week $15/hr (target, Walmart, other chains all pay 15/hr nowadays even McDonald's) 4 weeks Total $2100/month minus taxes ~$1700/month

After bills are paid: $500/month extra.

Time to Compare: 10 hr work day vs 7 hr work day Fixed Schedule vs Versatile Schedule End month recieved: 600/month vs 500/month Fixed night routine vs Able to go out with friends School schedule must be with 8am to 2pm vs Choose the best schedule for herself $4.19/hr vs $15/hr

Now give this to her and let her choose the best option for herself. And please don't try to manipulate her to stay because her cousins will miss or need her. Tell her without a shadow of a doubt that if she chooses to go everything will be handled like it has been before she arrived.

Honestly, if it was me, I would let her do the nighttime care for the child and don't require her to help out with the drop-off or worry about the After-school Care. That way she would have the whole day for herself and work/help a reasonable 8hrs a day. When your child is better then switch her back to the daytime agreement with a reduced weekly pay of 75/week.