Just raises concerns that the goal is getting immigration for the sister versus needing a nanny. You are not looking at after tax income. Over a 1/3 of their income would go for childcare for 1 child. I assume this has nothing to do with childcare and is a route to immigration. Childcare is expensive but most do try to find the most affordable option in order to potentially save money or allocate it to housing, transportation, etc. costs. You'll have to se what reply you get just warning you of these red flags.
Yes canuck, thanks. I know that if the employer is a relative, they are focused on helping the Employee to being a PR someday and not on the necessity of having a Nanny. I am fully aware of it, thank you. I still hope that an officer will approve.