You’ve been asked to work on a project that will impact another function in your company (or more than one function).
You could go at it alone but you know that those impacted will resent your lack of cooperation after you launch your project.
A better approach is to ask them for feedback before you launch. The problem with this approach is that it may be difficult and costly for you to make necessary changes at the tail end.
Better yet is to involve the other functions from the start. Announce your nascent project by email and invite all interested functions to nominate a representative to work with you. Set some gates along the way to ensure that everyone is aligned. Assign key tasks to the functions most impacted by those tasks. These additional steps might appear to slow you down but remember: slow is smooth, and smooth is fast. By involving the right people, you significantly reduce the risk of failure. More importantly, you make allies.
Nothing of significance is ever achieved by a single person.