Hi,
Is it possible to merge back double curved surfaces that are splitted without manually remodelling it?
With flat surfaces I can use merge faces, but with double curved not
Assuming they really were Split and have not been Shrunk, then you should be able to do something better than Merging.
Select one surface, detach it’s Trim curve. It should be the full original surface.
Then just delete the other ones.
Splitting does not alter the untrimmed surface. It’s still there after trimming. Untrimming removes the trim edge.