'Seinfeld' went off the air in 1998, with the characters locked away in a Massachusetts jail for one year because they broke the state's "Good Samaritan" law. As you should know if you understand the Toobworld Dynamic, their lives continued after the show ended. So by the year 2000, all four of them should have been out of jail. And who knows what happened after that?
So.... Approximately fifteen years have passed and that would be plenty of time for any one of them to have married and had children. If anybody was actually willing to risk marrying them, that is.
Yes, even George Costanza.
And if you can accept that as being pozz'ble, just pozz'ble, then this could be Estelle Costanza with her granddaughter by George......