It worked once. To check the workflow. Result was not good, so I tried from beginning. Result: no result or successful blend operation.
Here is my workflow:
1. Only the two fingers spline as base
2. Extrusion
3. Eleminate the spline on top/additionally? generated spline
4. Generate a simple spline through snapping points of the finger spline - trim of the two splines
5. Activate one part of the splitted fingerspline
6. Do blend
7. No operation is done
8. hmmm'...

Lara,
split finger edges using the trim tool then blend as shown in photo.
Cheers
Barry

Schema & Animation that i made shows the same Barry Method! :)

...o.k....this is not true...thank you for your patience!

Are all curves hidden before Blend of Edges?
-Brian

As you want (kill or hide) : essential is not select them for a Blend Surface(s)!

An easy way is use the Browser for disable curves! :)

Hi Brian,
Yes curves hidden only the edges of the fingers used.
Barry

Blend is so elegant! :)

Meanwhile I am online again.
Thanks a lot for your patience and helpful impulses. The hand is ready. And the blending is so incredible easy. I was so long on the BlendCap concept. Trimming the line in order to blend the tow parts of the spline I did not recognize in your ToDo-Posts...sorry...
best regards...

If you want more info don't hesitate! :)