What you need to do
Confirm that the proposed way forward is a project, not a programme. Make sure you have the ongoing commitment and support of the business. There must be a role responsible for making the investment decision, on behalf of the business (the Investment Decision Maker (IDM) role) . There must also be a Senior Responsible Owner (SRO) appointed, with personal accountability and overall responsibility for the delivery of the successful outcome; this individual must be able to commit adequate time to the project.
For cross-cutting projects, there must be a single SRO accountable for the outcome, from the collective activities of all the contributing organisations.