OFFSET SEVERAL CONNECTED CURVES

Resently, I'm working on the fins/transum for 3dimensionally curved piece of an architecture.  There are so many faces connected to generates a facade of it.  When I use Join curve and offset loose or offset script, it seems like grasshopper still treat the joinned curve as two separated curves and reverses the direction of the offset in some portion and it results on the separated segments of the offset lines inside and outside of the original surface.

The attached pics shows one example of what I'm talking about.

I have 2 questions regarding this problem.

1. How can I join those curves correctly? they are propperly located and meeting each other and still not treated as one single curve geometry. When I use panel and look what's inside and they say curve and line like curve.

2. How grasshopper decide front or back side of the surface?  or How grasshopper decide the original direction for offset?

If any thoughts or comments, I really appreciate them.

Thank you in advance.