This Microsoft Entra blog post will show how to connect another Microsoft 365 organization to your tenant and collaborate with them.
The Connected Organisations feature in Microsoft Entra is similar to creating a forest trust in Active Directory. It allows an organization to have full visibility to all the users in the connected tenant.
To connect another Microsoft 365 organization to your tenant, open the Entra admin Center
Click on Identity Governance
Click on Connected organizations
Click on Add Connected organization
In the search box, enter the tenant name or the partner organization’s external domain and review the result.
Follow the steps and submit the request to connect with an organization.