Integrating ADs to Azure AD

Hello Experts,

We have two Office 365 tenants - one for production and one for test purposes.

We have Azure tenant and the Office 365 for production users can also access Azure services.

I would like to allow Office 365 for test purposes users to also access the Azure services, so the two AD needs to be integrated and synched.

Can you advice whether this can be done and how, or what the best approach in this case is.

Thank you,

Tsveti