That is pretty much exactly what happened. I realized after writing about the Strettons (and then about the Woods, during the summer) that creating fleshed-out NPCs was a lot of work. Jeremy, Gemma, and Mrs Stretton all had pretty distinctive personalities. (The babies, Philip, and Mr Stretton were a bit more in the background.) As large-scale growers and manufacturers, the Strettons also filled a worldbuilding niche in various ways.

An NPC half-blood who got bounced around endlessly would have been fun. We could've done that with Su Li and let Padma tell that story.