Your question is Influence Without Direct Authority. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are leading a cross-functional initiative where several key contributors do not report directly to you. You still need their time, alignment, and follow-through to keep the work moving.
How do you influence team members who do not report directly to you?