If you want to manage users and groups from both corporations in a single location, you need to consolidate your Atlassian Cloud organizations. This can be done by transferring all product instances in one organization to another. After the transfer, the unwanted organization is deleted1. This feature is called Transfer products and it is available from the organization settings2.

The other options are not features that can help you merge your organizations. Organization insights is a feature that provides analytics and reports on your organization’s users, products, and security3. Release tracks is a feature that allows you to choose when your cloud products receive new features and improvements4. Verify domains is a feature that allows you to manage the Atlassian accounts of your users and apply security policies to them5. Identity providers is a feature that allows you to integrate your organization with external identity services, such as SAML or SCIM6.

References :

Should I merge my Atlassian organizations?

Transfer all products to another organization

View organization insights

Choose a release track for your cloud products

Verify a domain to manage accounts

Manage users from your identity provider