The Chief Product Owner
A large agile project consists of many small teams. Each team needs a product owner, but my experience suggests that one product owner usually cannot look after more than two teams in a sustainable manner. Consequently, when more than two teams are required, several product owners have to collaborate.
This puts us in a dilemma, as it conflicts with the Highlander Principle, which states that there should only be one product owner. The solution is to introduce a chief product owner. A chief product owner is responsible for the overall product, guides the other product owners, and facilitates product decisions.
There are two ways to apply the chief product owner role: working with one potentially large and complex product, or breaking up the product into multiple, independent sub products.
Option 1: One Product
If you develop one cohesive product with lots of functionality, you are likely to end up with a hierarchy of collaborating product owners with a chief product owner at the top, as the following image shows:
In the picture above, the chief product owner is responsible for the overall product whereas the other product owner manage feature sets or individual features.
Option 2: Product Family
The second option is to unbundle the product into vertically-aligned, focused sub-products that can be managed by one product owner, as the following image illustrates:
The advantage of the product family approach is to release the individual products separately and to package them to product variants. A flatter project organisation also means less overhead and faster decision making. The product backlogs are focussed and more concise reducing the grooming effort and increasing transparency.
If you work with more than one product owner, put one individual in charge of the overall product. As your product grows and becomes more feature rich, consider breaking it up into focused, vertically-aligned products that can be managed by one product owner and developed by no more than three teams. This allows the product owners to control their product, reduces decencies and overhead, and speeds up development.
You can learn more about scaling the product owner role by attending my Certified Scrum Product Owner training course.