Hi Drill,
I meant what Michael shows here:

https://moi3d.com/forum/lmessages.php?webtag=MOI&msg=10365.8

""""""if you have the hole where there is not latitudinal line"""""

Surface edges don't stop you from being able to untrim the surface. That would be an indication you need to separate more, or just select more edges for the untrim to work (usually resulting in more "re-trimming to get back all the WANTED boundries)