Don't get a sister

Raj's cousin got a baby girl. I showed Vaibhav and Karthik the baby girls photo and told them it is their sister. I asked them if we should bring a sister. She could play with them and they could take care of her. Vaibhav made a face, thought over and then said, "Don't bring any sister. We are already two kids here." I replied, "so what we can have another baby, she will be cute and nice.". Vaibhav then told "Don't bring any sister, when I grow up I will get a baby. I will give that to you, you can care for it and play with it.". I couldn't stop laughing for hours.