Surface from series of curves

Hi there, 

I can't figure out how to create a surface from the following curves. I have tried using the plugin "minimal surfaces" but I cannot seem to get the surface to form correctly. I have attached a sketch of what I'm trying to achieve. 

Tried using the following Rhino commands too and it still wont work:

Network curves

Patch

etc. 

Any help would be great. 

Many thanks,

Tom