I think common for new carer to feel they need be everything for everyone one. Children are important but that not mean we have accept every and any imposition parent would want us to.
Set boundaries of service. Determine process for interview and not be afraid to enforce boundary. Without it, you be insane by end of first year. It a two way interview so if parent demanding or unrealistic, take that information as gift telling you what they be like long term. And never be afraid to say no - and you not have to justify your decision.