Update layout for the frequently bought together module

Hello.
I need to add data attributes for the selects in frequently bought together, how can I do this?
I’ve installed child theme, duplicate folders and files ‘class-frontend.php’, and try to add different attributes, but they are not visible, and I understand that this file isn’t overridden, how can I do this?

Also, I want to describe my target.
I have Product #1 with variations, and Product #2. When I choose variation in the Product #1 I want Variation of the product# will be updated.