L.A.
I am so sorry about your father in law.
When our daughter was around this age, one of the mothers of one of her classmates in preschool was killed in a tragic accident.
This was a child and a mom that had been there as long as we had. It was just heartbreaking.
Our daughter always did best with honesty and with books. It seemed to be a great way for her to ask questions.
Lifetimes was one of the best that I purchased.
http://www.amazon.com/Lifetimes-Beautiful-Explain-Death-C...
I also purchased some books about when a child loses a parent, a grand parent and a pet. These books came in handy for the deaths of other friends and family members for many years.
I let her ask any questions and just answered in simple answers. At school they also spoke about this subject. I was worried about what to expect. They told me to just answer in simple answers. that she would be contemplating this information and ask what she needed to know.
A few days after this news, she asked. Because "Marks mommy is dead, where is he going to live?" I said "he is going to live with his grandparents. You know them." A few minutes she asked, "If they die, how will he go to the grocery store for food? He is a little boy and cannot drive a car!"
I said, "well we can take him to the store and he can live with us." " Her answer? "That is a good plan."
So that is how she handled her concerns. She just wanted to know "the plan.".
So keep it simple. They do not need a long drawn out explanation or fantasy. They just need to have their concerns or questions answered "honestly."