In the .gh-file I have manually created a curve that sort of blends from one curve to another.
The original curves (circles) are on separate planes.

If I can make this in grasshopper I will then loft between similar curves.

Any suggestions how this can be achieved?

I should add that what I’ve tried so far is divide the curves to get a number of points.
Then deconstruct those points and using two graph mappers, one for each set of points to alter the points in x and z respectively. I think that what I’m looking for is something that could give me more symmetric results.

Wow, thank you very much!
Setting the start of the subcurves together with setting the bulge of Connect curves gives a fantastic control over the result.

I haven’t used the biArc and judging by it’s name I thought it would make an arc in one plane.
This was interesting with the ratio of the biarc segment input.

Instead of using your list of points (a separate issue, really), each slider can designate a point on one of the two curves. And instead of flipping curves, you could reverse one or both of the tangent vectors passed to BiArc(not shown).

Or you could connect all four of your points on one circle to the four points on the other circle; they Loft very well! Interesting surface shape possibilities here: