Experience of managing successful delivery alongside other suppliers

Problem: HMRC required an Integration-team to work alongside other suppliers.
Our team:
Discovery
-Agreed goal/problem-definition with stakeholders.
-Assessed user-journeys/personas; in-collaboration-with other teams (Cap-Gemini/Accenture/Equal-Experts/In-house).
-Identified client-constraints; conducting cross-team-workshops; identifying overlaps/gaps across 4 value-streams in SAFe-programme/improvements/cost-savings.
-Agreed cross-team Alpha-backlog with success-measures; ensuring cost-effective, viable-service.
Alpha
-Adopted risk-based-prioritisation; selecting high-risk integrations with Digital-Frontend/Rules-engine/finance-system/DataStore.
-Focused on end-to-end journeys (with other delivery-teams through continuous-integration/delivery) based on user-defined scope with continuous-assessment through prototype-demonstrations.
-Openly shared findings across all delivery-teams through JIRA/Confluence.
-Agreed Beta-scope, success-criteria, common-platforms for reuse, budgets and team.
Outcome: Successfully delivered CDS, BSP and MASP programmes/project; establishing development-platform/processes with internal/external teams.