Polarbear, i agree that kids wanting a different sibling configuration is normal. Dd has been asking for a sibling for 2 years now and I did not pay much attention because of what you and others here mentioned. I only started worrying recently because of her daily pleas for a sibling followed by meltdowns. i am not sure if that is normal. Today at the thanksgiving table, she insisted on setting a place for her doll. We had a lot of company so squeezing in an extra place at the table was not easy but we did it to avoid meltdowns. Hopefully, she will come out of this phase.