Multi-Forest AAD Connect (Office 365) to New Azure AD tenant-Office 365 Tenant

Hello Experts,

Looking for your expertise on following scenario :

We have two on-premise Active Directory Forest with separate Azure Tenant (Office 365)

1. Forest A.Com -->AD Connect-->Azure AD (O365 Tenant A)

2. Forest B.Com-->AD Connect-->Azure AD (O365 Tenant B)

Now, we want to consolidate both Azure AD (O365 Tenant A and Tenant B) to a single tenant called "Tenant C", but on-premises AD DS will be remain same.

As, we can go "Multiple forests, separate topologies" scenario on below post:

https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-topologies#multiple-forests-separate-topologies

But, same time we have to migrate the mailboxes from Tenant A and Tenant B to Tenant C, 

Here are the steps what we are planning:

1. We can do initial sync Forest A -->AAD Sync --> Azure AD Tenant C ( for creating the users in Tenant C) "The UPNs of the users in the on-premises Active Directory instance must also use separate namespaces"
2. Use the 3rd party tool to move mailboxes from Tenant A to Tenant C (to map the UPN) -Stage-Sync (95%)
3. Same process for Forest B and Tenant B.
4. Configure AAD Connect (multi-forest A & B) to Azure AD Tenant C and start sync (over night/weekend) with matching the namespace.
5. Cutover the mailbox migration to Tenant C
6. Remove the Azure AD Tenant A and Tenant B from AAD Connect

Your expertise will highly appreciate to correct me on this.

Thank you!