Relations, please tell me I can select all collections

Hi I have a products collection and a voucher collection.

I make a relation from products to vouchers on a one to many basis.

When I go into a product record I see the voucher relation field and the individual voucher items, but I can’t see how I can highlight and select all of them in one go rather than adding one by one.

Please tell me this is possible or there is a workaround to achieve a product query also showing all available vouchers.

I’ve tried a component that integrates all the vouchers, then link that component to the product, but when I run a product query, I just see the product and the component top level (not the underlying voucher items).

Help greatly appreciated.

Thank you.