Bishul Akum in my home

Question

Can a babysitter/nanny fill a pot with water, ignite the flame, get the water boiling and put in the ingredients to cook in my home for my children to eat? Example, rice or bean soup or macaroni in two weeks after pesah. If the answer is no Can a babysitter/nanny fill a pot with water, ignite the flame, get the water boiling and wait for my wife to put in the ingredients? Secondary question, instant soup mix, such as knorr instant soup packages. Can the babysitter/nanny boil water and mix the package to give to the baby to eat? Thank you, Hazak uBaruch Sander Silvera