Restrict which products can share a cart

Two independent controls in Settings → POM Tweaks → E-Commerce → Cart & checkout determine whether different products can be purchased together. WooCommerce must be active. Both controls allow multiple units and variations of the same parent product; neither imposes a one-unit limit.

Allow only one distinct product

1. Enable One product per cart and save.
2. Optionally enter Notice when products cannot be combined and save again. Leave it empty to use the built-in explanation. The custom message is plain text and supports the site’s configured translations.
3. Add one product to a cart, increase its quantity, and try adding another product. The different product is rejected with a notice.

Two variations of the same variable product can share the cart. If the cart already contains different products, the customer must remove the conflicting items before checkout. The check also runs in classic checkout and Cart/Checkout blocks.

Mark only specific products for separate purchase

1. Enable Products purchased separately and save.
2. Edit a product under Products → All products.
3. In Product data → Inventory, check Single product, then update the product. For a variable product, configure the parent product.
4. Try adding that product alongside an ordinary product, in both orders. Both combinations must be rejected. Additional units or variations of the marked parent remain allowed.

Unmarked products may share a cart when One product per cart is disabled. When both controls are enabled, the store-wide restriction is stricter and applies to every product. Existing product selections are retained when this tweak is disabled and take effect again when enabled.

Verification and limits

Verify an empty cart, repeated units, two variations, a marked product and an existing mixed cart. Customers receive an explanation instead of a silent failure. Existing orders are not rewritten. Native quantity limits such as Sold individually still apply independently.

These controls guard normal WooCommerce cart and checkout flows. Integrations that create orders directly without cart validation must enforce their own purchasing policy. Verified POM composite component rows are counted with their parent container. A bundle integration can also group its required products with the main product after verifying their membership. Other cart products still count separately. Simply naming a product a pack does not create a group.

For example, a Fenómenus pack managed by Pomatio includes the matching POM AI Single subscription and Pomatio Tier 1 plan for its billing period. Those required lines can share the cart with Fenómenus even when Single product is checked. Unrelated products and variations outside the selected pack remain subject to the restriction. The bundle owner still enforces the required contents.

To remove restrictions, disable the relevant tweak or uncheck Single product for the affected product and update it. See also Quantity discounts and Order products in the cart.