The phrase "to join the initiative" means to become a part of a particular plan or action in order to support and contribute to its goals or objectives. Full definition
Total, which joined the initiative in its very early days, was the first company to do so. (cnbc.com)
All nine of the schools have continued to offer the programme and will be involved in helping the schools now joining the initiative to implement the CP. (education-today.co.uk)
About 10 energy companies joined an initiative that was trying to figure out what blockchain technology could do for their business. (profitconfidential.com)