New conjecture:
Conjecture $latex \mathrm{up} (f \sqcap^{\mathsf{FCD}} g) \subseteq \{ F \sqcap G \mid F \in \mathrm{up}\, f, G \in \mathrm{up}\, g \}$ for all funcoids $latex f$, $latex g$ (with corresponding sources and destinations).
Looks trivial? But how to (dis)prove it?
Can you be more specific about the content of your article? After reading it, I still have some doubts. Hope you can help me.