- In the UV editor, select all UV:s - Convert selection to UV-borders. - In the 3d viewport, convert the selection to contained edges. If you by any chance would like to go the other way around, selecting all hard edges, to split the UV:s, you can do that using conditions in select > select using constraints
Hello. I believe that in the UV editor you can select the edges where you have the splits and it should select them in the perspective view then you can set them to hard edges. You should be able to select the uvs as well and convert them to the contained edge selection.