Some add-ons aren't optional. Reqmunk requires a companion product — laces with shoes, a warranty with electronics, an install kit with a rack — before the trigger product can be bought. Target products, tags, or whole collections, and write the message shoppers see. The product page gates Add to cart until the shopper picks the companion, then adds both together. Checkout validation blocks carts that drop the add-on. No theme code edits — one app embed. Free plan includes one requirement set.

• Gate add-to-cart until the shopper picks the required companion product
• Checkout validation blocks carts that drop the required add-on
• Trigger by product or collection; write the message shoppers see
• Selector card shows thumbnail, variant prices, and a running total
• No code edits — one theme app embed, enabled from the app