Poor child

So here is a weird story about a kid in my preschool class. Two weeks ago our theme was "families." We talked about a different family member each day-moms, dads, siblings, grandparents, aunts/uncles/cousins. The day before the "dad" day this mom came in and asked if she could talk to me. I knew that she had just got divorced and her and her boy were living with her mom. I figured she was going to tell me that when we talk about this boy's dad to say something to the extent of "he lives in another house" or "even though mom and dad aren't married it doesn't mean he isn't your dad." Boy was I wrong. She told me that they are telling the child that he doesn't have a dad. This boy is only 3 years old. Very confusing for a 3 year old boy. The man she was married to, living with and since this boy can remember has always been known as dad isn't his biological father. Once the divorce was final she had this idea to say that he didn't have a dad. She then looked at her child and said "we will find you another one some day." I think I just stood there and didn't move for like 5 minutes after she left. When it was time for "dad" day we just skipped over that child. There was no way I was going to say "(insert child's name) doesn't have a dad."