Enterprise distribution of an iOS app from a third party developer

I've been asked if we can distribute an iOS app internally (via AirWatch) which has been developed by a third party. We can't use the App Store is because the developer is re-branding their app for our company.

So they would have to sign their app with our Distribution Certificate but what is the safest way (for us) to allow them to do this?

You should sign the app yourself. so the 3-rd party developer have no access to your certificates.

1. Enroll to Apple Developer Enterprise program .
2. Create enterprise certificate.
3. Create provisioning profile and any other certificates that the app needs (the developer should know which extras are needed).
4. Get the ipa file (the app) from the developer.
5. Resign the ipa with your own certificate you created earlier - to do so use the iReSign tool.
6. Diatribute the app via your MDM (AirWatch).