When assembling the right sill we realize that we are missing one part; the rear part of the hot air duct for the rear passenger floor, Citroën part number D 643-96.

So just as we think we finally have almost all sheet metal parts we need, the hunt is on again...

Edit: Thanks to the kind help of a true Citroën enthusiast I have now got a used part to use as a template for producing a new air duct! Thanks Mårten!