Is there a way to join to co-planar trimmed surfaces which meet at a point?
I have a definition which is creating a polygon from rhino points and then creating a trimmed surface from this. However when the rhino points are moved in some configurations the polygon lines cut back on each other and this causes more than one surface to be produced. This then throws off all my logic downstream.
Any direct solution or work around would be appreciated.
Not in Rhino. In order for multiple surfaces to be joined into a single polysurface they must share at least one edge. Meshes can be merged into a larger mesh, even if the pieces are entirely disjoint, but for surfaces and breps a non-zero overlap is required.
However your question seems quite specific and as @Joseph_Oster said; no-file, no-help.