I have tried for a long time but I just cannot fill that surface (black arrow). I understand that the problem (presumably) is, that the endpoints are not on one surface. But I cannot find where.
The object is the filling between chairs (blue arrow).
thea2.skp (456.8 KB)
PS: this will be a 27 seat small theater in a resort on the Island “Koh Mak” in Thailand. One night for free for the problem solver