As you can see in the attached files I try to fill thee gap between the surface. Is someone able to help me figure out a solution for this? Will much appreciate your help!
The Fill Surface should do what you want, just make sure you select every edge around the boundary of what you want to fill. From the first image the 3D sketch you selected wouldn't be sufficient. Then it's a case of playing around with the edge settings to get a decent result.
can you add your file for us to look at?
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