S.K.
Dear M.
I am sorry for the loss of your father. Seven years ago my father in-law passed away and he had lived with us. He actually was able to spend time with our two daughters day in and day out. The girls were 10.5 yrs and 8 yrs old.
Now they were not as young as your daughter but the closesness may be compared.
I let the girls talk about Dad as much as they wanted. My husband and I went out a bought them both a teddy bear as an anchor. We told them the bears were from Grandpa. (You see my father in-law passed away a week before Christmas) These bears were helpful as when the girls got sad we told them that Grandpa wanted them to be happy with their bears.
So my advise is, when she is up to it let her speak about her feelings towards him. Let her say she misses grandpa and judge the amount of time necessary because 4 year olds need to live for the moment and the days ahead. You can show her things you and he did together when you were a little girl. Your Dad is going to remain alive through your stories. He can never be forgotten. She will be curious and can't wrap her head around the Grandpa is in heaven but she can learn he is happy and suffers no more. My prayers are with you and your family. Time is your friend. Take it day by day. Grieve and in time it will be more tolerable because it is something we all need to experience and cope with.
All the best. S. K.