Adding an external development team still leaves decisions for your organisation to make. Someone needs to choose priorities, explain the business rules and accept the delivered work.
Name a product decision-maker
Give the team one clear route for resolving conflicting requests. The decision-maker needs time to review progress and answer questions. A contact who can only forward messages may leave delivery waiting on decisions.
Agree how work is accepted
For each feature, describe the expected behaviour and the evidence needed for acceptance. Include error cases and access restrictions where relevant. Decide who supplies test data and who reviews the result before the feature is scheduled.
Keep operational ownership explicit
If your team runs production, involve it in deployment and handover planning. If the supplier provides support, document its scope, hours and escalation path. Identify the person authorised to make decisions during an incident.
Use the first release to review the arrangement
After a small, agreed release, review what delayed the work: unclear requirements, unavailable reviewers, access problems or technical dependencies. Adjust the working process before expanding the backlog.
An external team may add delivery capacity. It cannot independently decide your business priorities. Include that internal responsibility in the staffing plan.