Extra baby unrelated to parents

After pregnant sim gave birth to baby and carried on playing, I entered building mode and changed buildings, exited and returned to live mode then entered create a sim and made adjustment to mother's likes/dislikes. Upon returning to live mode again the construction changes were reversed and the mother was pregnant again. The baby that was already birthed has no family connections at all. The new baby is born with normal settings and relationships. At first I was completely unable to care for the first baby but after reloading a few times I was able to start caring for the baby and eventually given the option to take responsibility for the child.