Alright Barry-H, I'm a happy Man, it's PERFECT, exactly what I was asking for. Many many thanks Barry-H.

I tried to do a "multiple network" many times, hoping the inner edges would be smoothed as the inner arcs are, but didn't get that I have to specify the order. Forgot to ask about it in my previous posts.

I thought this was possible if curves are correctly setup with tangency along them, I carefully did it as it should be here.

Now I can do the bottom part, and draw any shapes with nice stream curves and surfaces. Cool, it was worth to try, spend time on it, and ask here. I really learned a lot already.

Look at these control points, isn't that a nice flow surface ?