I’ve tried the component ‘Points trim curve’ from the Pufferfish plug-in as well as trying to trim with brep, however I think the missing piece/knowledge that I’m unfamiliar with is the purpose of ‘flatten’ or ‘graft’ or when to use those on an input?
Pull Curve to surface, then Split Surface with the curve. Then figure out which piece(s) of the surface you want to keep and which to ignore. There will be two pieces in the “doorway” since the seam of the surface appears to go down the middle.
The portion I need assistance with is within the purple group box which uses standard grasshopper components. The other plugins are for post-process steps, so they’re not imperative to the geometry I’m trying to achieve. Hope this helps to clarify!