Jack and Lily should follow the Hispanic custom and use both surnames. It makes it easier to know who’s who that way.

>Jack
Jackson Wylde becomes Jackson Wylde Kelly.

>Lily
Lily Pak becomes Lily Pak Wylde.

In these cases, when there’s a divorce or something similar, the child takes the mother’s surname first and the father’s surname second, otherwise she would be Lily Wylde Pak.