Hi Rhumba, can you please post a .3dm file with some examples of what you're describing? That would help clarify things.

It sounds like the main issue that you're running into is that Blend is kind of bit too "bare bones" right now, it doesn't let you pick a set of edges to blend between, you can only blend between 2. I might be able to tune this up, I'll take a look.

One thing you can do as an alternative right now is to construct things so that they touch along a common edge, then join them together and use Fillet instead of Blend. Inside Fillet there is an option to do a blend style shape as well, that ends up being the same thing as Blend, just with it trimming back from the common edge to make some room whereas Blend doesn't do any trimming and expects there to be a gap between edges.

- Michael