We have actually had this happen twice. We adopted Internationally and were called by our daughter's birth family to take her newborn baby sister. We adopted our daughter at three weeks, our second daughter, her sister, at eight weeks. Then, while doing foster care, we adopted a little boy. He was placed with us at 2 days. His birth mother was in her late 30's. We got a call 15 months later to take his baby brother. They are now 2 and 3 and mom is in her 40's. We have never met her but we are thinking she is done having babies. Our younger children are now 10, 8, 3 and 2, our older children 26, 24, 21, and 20. We feel our family is complete but we take each day as it comes. We still foster, but only one baby at a time.
And yes, we are also grandparents to two amazing little girls, ages 3 and 1. It is always good to talk about what you would do but, really, none of us knows what the future will bring or where we will be when that call comes.
Maryann