First time you've mentioned a wartime plance wreck... and really interesting about the personal connection.

Yes, you'd have had issues at CDG for sure trying to bring bits like that through.

Make sure any bits they do recover are obviously not weapon like; they do screen all cars at the ferry terminals ( you won't notice it, but they do... not as thoroughly as on the Euroshuttle though* )

*If their ferry back is cancelled and they get offered a choice of the Euroshuttle or waiting for a later boat - they should opt for the later boat even if it's several hours... they'll almost certainly get taken apart at Coquelles...

PS This is the half snipe...