I know that there is probably a way to do this without JQuery but I had a go at doing it with JQuery anyway and realized I didn't know how to access specific sublist fields. Hence my original question

So you just want to change the value in frontend without saving it to the server?

I'm using a client script to insert field options into my sublist select field based on the value of another field. My problem is when a value is selected, then the field options change due to the other field. The currently selected value stays in the select field even although it is no longer available in the select options