To encourage more members to share their projects in the online group, the manager can offer free yarn skeins to first-time posters. This incentive can motivate members who might be hesitant to share their work by providing a tangible reward for participation. Additionally, it can create a positive feedback loop, where initial engagement leads to more frequent contributions and a more active community. By fostering an environment where members feel valued and rewarded for their contributions, the group manager can increase overall participation and engagement.