hi @starry ,
That a good question. Thank you for posting it. I removed the community-components tag and the show-and-tell and the tips-and-tricks tag, because this is not relevant to those tags. This is merely a question.
I think you would benefit from using pattern matching callback. Here’s sample code of an add/delete button. I recommend reading over it until you fell comfortable with the code, then try to change the checkboxes into dropdowns.