If customer buys five quantities of my this product https://khaikandles.com/product/wax-melts-warmers/, I give him 6th one for free and that is added automatically at the cart page and I am using BOGO plugin for that.
My above product has got seven variants. Right now only customer can buy one variant in 5 quantities in order to get the 6th one for free.
What I want is if the customer wants a combination of product variants Like 2 Beach linen (it is variant name), 2 Lemon Pound cake (it is variant name), and 1 Strawberry guava (it is variant name), and then they can choose a 6th variant to be automatically added free in the cart?
How can that be done, please?