PMP Practice: Break Down Scope

Brigitte Schäfer-Winkler is leading an agile project for Cheerful Entropy Labs to develop a multiplayer puzzle game. During sprint planning, the product owner proposes adding a new social feature that allows players to create custom avatars with user-generated content. The development team expresses concern that this feature is significantly larger than initially understood and could span multiple sprints. Two team members believe it should be split, while the product owner insists it must be delivered as a complete feature to provide value. The team's velocity has been stable at 35 story points per sprint, and this feature is currently estimated at 21 points. Which approach would be MOST effective for defining the scope of this feature?