Hi netappmagic,
Good question!
When migrating data from 7-mode to cDOT, we need to consider two different interfaces:
1. The Data Copy Interface, that is the source IP address which 7MTT is using to migrate data with snapmirror from source controller to destination controller. This is chosen by default in 7MTT and is a mandatory configuration.
2. The NAS Interface, also known as the transition LIF if using the 7MTT command line. These are the interfaces which your NAS/NFS clients are connecting to the storage. 7MTT reviews your source 7-mode controller interface configuration and can re-create the source interface as a new Data LIFs on the destination SVM. The Data LIF is made online during the cutover event. This is an OPTIONAL configuration in 7MTT which is not required for a 7MTT project to be successful. What is required for a successful migration is for you to understand how your NAS clients are connecting to the source 7-mode controller, and how they will be connecting to the destination storage cluster / SVM. Whether or not 7MTT manages any Data LIF provisioning is optional and up to you.
You can view the Data Copy Interface which 7MTT is using for snapmirror by viewing the 7MTT CLI command: transition show -s <session name>. You can get a list of sessions by invoking transition show without any parameter.

Note: Multipath IP address is also highlighted. If you have multiple SnapMirror interfaces or would like attempt to increase snapmirror bandwidth, you can optionally specify a SnapMirror Multipath interface but this is not so common.
You can view any NAS interfaces aka Data LIFs which 7MTT is going to manipulate by using the 7MTT CLI command: transition lif show -s <session name>

In this screenshot 7MTT session hadrianpilot_standalone did not specify any Data LIFs to be provisioned or migrated.
In 7MTT session donotmoveip_standalone, we indicated we want 7MTT to provision a new LIF on the target SVM for use by NAS clients during cutover. As mentioend earlier in the thread, 7MTT does not perform any work to update DNS or your client configuration to inform them of the new interface, that is up to you.
If you desire to understand the destination storage cluster interfaces which are used for SnapMirror replication, and that 7MTT will use to migrate the data with, you can check the storage cluster CLI like so:

If you desire to understand which LIFs are already provisioned on the destination storage cluster, check the storage cluster CLI again. These could have been provisioned by you or by 7MTT if you had selected "New LIF" in the previously indicated screen shots.

Hope this answers the question. If so please mark it as so / hit the kudos button. If not... you know where to find me 😃
Hadrian