I have a forest with 1 root domain and 5 child domains.
For 2 child domains the dns information in the root forward lookup zone as a new domain and for rest of the 3 child domains we have a delegation which is pointing the dns information for these domains to name servers in these child domains.
I am given the task to move the 2 child domains from root dns forward lookup zone to each child domain FLZ and create a new delegation to point to NS records.
I am attaching a file showing the dns structure, with 2 screen shots in it. Showing the changes to be done as in the other 3 child domains.