Hi Lemo, could you please post a .3dm model file with your curves?

Getting the actual curves to look at really makes it easier to understand what you are describing.

It sounds like probably your curves are touching each other with a sharp corner rather than being tangent where they touch one another.

If you join 2 curves together, it will make a curve made out of 2 segments, and when you do an offset the offset segments should get extended to touch one another.

If you want to have only one segment in the joined curve, then you can turn on Control points (Edit/Show pts), and select the control point where the segments are joined and delete it, that will fuse those 2 segments together into just a single segment.

I could give you some more specific advice if I had the model file to look at though.

- Michael