Hi@EVTECH#18661
Thanks for your post.
After having a look at your site:
I understand that you use variable products. BOMs are set at variation level, so you can decide which BOMs link to each variation. When a variation is sold, the stock of the linked BOMs will be discounted.
If you don't use variations for all the available options, it won't work. You can't modify the linked BOMs dynamically.
However, it would work if these optional items were added to the cart as separate products.
Sorry if I'm not clear. I can't be more specific without more info.
Hope this helps,
José Andrés