> ## Documentation Index > Fetch the complete documentation index at: https://docs.mercurjs.com/llms.txt > Use this file to discover all available pages before exploring further. # Order Group > Wrap a multi-seller cart into one shopper-facing order made of independent per-seller orders. Use Order Groups to turn a single customer cart that spans multiple sellers into one coherent order for the shopper. A marketplace cart can contain offers from several sellers at once. On checkout, Mercur splits that cart into one child order per seller and wraps them in an **Order Group**. This is the aggregate the shopper sees as "their order". Each child order is then fulfilled, returned, and refunded independently, while the group gives you a single handle over the whole purchase. An order group is the `OrderGroup` entity. It lives in the **Seller module** (id prefix `og`), not a module of its own. There is no `ORDER_GROUP` module key. Resolve its service through `MercurModules.SELLER`. ## Key features * **Multi-seller checkout:** one cart with offers from many sellers becomes one group of per-seller orders. * **Human-readable id:** an auto-incrementing `display_id` the shopper and operator can reference. * **Immutable cart link:** a read-only `cart_id` back to the originating cart. Carts are frozen after checkout. * **Computed totals:** `seller_count` and `total` are derived at query time, never stored. * **Independent child orders:** fulfillment, returns, and refunds happen per seller order. * **Scoped visibility:** admins see every group platform-wide. Vendors see only their slice. ## Get started Learn how the domain fits together. The aggregate entity, its `display_id`, and the read-only cart link. How a multi-seller cart is split into per-seller child orders. Why `seller_count` and `total` are calculated at query time. ## Examples Build against Order Groups in your own code. Load a group and its aggregated child orders. Page through groups, optionally scoped to a seller. Complete a multi-seller cart into a group of orders. ## Resources Data models, links, workflows, service methods, and events for Order Groups. The `OrderGroup` entity and its fields. How order groups link to carts, orders, sellers, and offers. Splitting, retrieving, and listing order groups. Seller module methods for working with groups directly. Events emitted as order groups are created.