Sweep2 needs the capability to use a point as a rail (not just as a section). See the attached for an example where neither the other rail nor the sections are straight lines. Sweep2Pt01.3dm (102.9 KB) The surface in the example was created using a non-obvious work-around.
Strange request because finally you’ll have only one rail, if the other is point .
If you make a sweep one with blue line as rail , and 2 others green curve as section, you got the result you have on your example.
not sure to understand 
[quote=“Cyver, post:2, topic:30795”]
If you make a sweep one with blue line as rail , and 2 others green curve as section, you got the result you have on your example.
[/quote]This only works with multiple sections with a common end point.
Example with one section. Sweep1 gives a different result. Sweep2Pt1Sec.3dm (117.7 KB)