Consider the following after partner selection:

• If possible, try to reduce the dependency as much as possible. Have a single partner/advisor who manages ISV and the development partners.
• Get the budget approved and have all the invoices billed through the partner. This way, the customer doesn't have to deal with multiple parties.
• Share your project plan with the ISV partner and align their delivery dates according to your schedule. Update your project plan to include the key ISV deliverables.
• Have them attend weekly meetings for status updates (if they are working in parallel on building the solution).
• Plan the code and configuration changes from ISV that must be incorporated into your development and other environments.