Get union of select_multiple responses

Hi. Long-time lurker first time poster.

I am having trouble figuring out how to take the union of different select_multiple responses.
More specifically, I ask a series of select multiple questions whose choice sets overlap and then want to do a repeat group over the unique items selected

For example, if a= "apples bananas" and b= "apples oranges", what would be the closest
approximation to a function union(${a},${b}) that returns "apples bananas oranges"?

Thanks in advance!

Congratulations on your first post @jedsilver! We're glad you're here. When you get a chance, please consider also introducing yourself on this forum thread. I'd also encourage you to add a picture as your avatar because it helps build community!

I thought about your question for a while and can't think of a way to make it happen. The function you're asking about isn't one of the available form operators and functions, and not part of searching and matching strings.

Can you provide any more details about the specific questions and option sets you're working with? Maybe someone has a clever suggestion for redesigning the questions to get the same information a different way?