It would be a welcome option to add a continuity option for the extreme edges (g0, g1 and g2). (Currently the command includes only the modification with the ALT keyboard, convenient, but does not have a snap line that establish allows to the exact linearity with the extreme edge, everything happens in an arbitrary way).
In the example we see how the blend between the surfaces a and b performs a continuity with the extreme edges only of type G0. (image on the left).
Remember that the VSR plug-in allows you to do all this with precision. It would be nice if Rhino could implement this …
