Why not rewrite the following commands: Extend crv on srf, srf extend and offset crv on srf? It would be useful to be able to display a preview, and add the handles, so as to extend the curves and surfaces in an interactive way. The first command is missing an option of extension of the soft type (G2); The second command has been that many years ago, only slightly improved.
We give more value to these commands, they seem sketchy! Are commands that are used by everyone, not just a few categories of users.