Hi
This is Rahul Bansal, an Microsoft expert and consultant with an extravagate experience of 14+ years and extensive experience with Microsoft 365, where we have performed several migration with multiple domains into single tenant only.
I have understand your query into this and we are very much know, how to resolve coming issue with proper manner of resolution.
Please initiate the chat with us for more to get quick resolution onto MS365.
Thanks & Regards
Rahul Bansal