Carl Dalton

In an alternate timeline in which the UK-201 never crashed on Dido, and was later further modified itself,  was the son of Vicki Pallister and Jeran Dalton, and the older brother of Maria Dalton. In a previous timeline, Carl had never been born and his parents instead had a daughter named Carla.

Changing timelines
Carl was born on Astra in a branching timeline created by his mother Vicki. When one attempt to save her father from his death in a meteor shower ended poorly, Vicki tried to return to the timeline of her married life with Jeran and her two girls Carla and Maria. However, very small changes to Vicki's approach, and pure chance, meant Carl was born instead of Carla. Maria was also quite different.

Vicki was horrified by the realisation that she could never see her daughters as she knew them again. This convinced her to return to the UK-201 's fateful flight and allow the prime timeline to play out.

Prime timeline
After Vicki escaped the alternate timeline and return to travelling with the First Doctor, Carl never existed. Vicki, however, could still remember her experiences and chose to preserve the memory of her family. (AUDIO: The Crash of the UK-201)