The finding inspiration part was the speculation, not the staying in Paris part.
Ah - I now can see what you mean; thanks for the clarification! :-)
Just a little update, because I knew there was a reference about Hergé and Paris in wartime that I couldn't put my finger on this morning, but I have now tracked it down.
In Tintin et Moi: Entretiens avec Hergé
, the Numa Sadoul book of interviews, Hergé himself talks about his journey to Issoire.
He was a reserve officer in the Belgian Army - he wryly comments on the efficiency of the military machine when he says that they really made use of his "skills" by placing him, a French speaker, as a trainer in charge of a Flemish-speaking machine-gun company!
It was, he says, on the 10th of May, 1940 that the order came to withdraw to France, as the Germans had entered Belgium. At that time, since the 10th of the previous month, he had been on three months sick-leave, but he and his relatives set off.
"(On) the 15th we were in Paris, and the 22nd I found myself, with my wife, sister-in-law, niece and my Siamese cat, in Saint-Germain-Lembron, near Issoire, at the home of artist Marijac, who was at that time at the front."
So we now have the exact window of opportunity for Hergé's passage through Paris in 1940 - even allowing that he may have got there before the 15th, and left after, it can't really be more than four or five days maximum, to allow for the travel from Brussels and onwards towards Issoire.
Marijac was the pen-name of Jacques Dumas, who fortunately survived the war, and died at the age of 85 in 1994. He drew the cowboy cartoon Jim Boum
for Cœurs Valliants
,so presumably Hergé was either already in contact with him, or he was directed there by Marie-France Sebileau, Abbot Courtois, or their colleagues during the stop-over in Paris.
It was while at Marijac's house that Hergé either left for safe-keeping, mislaid or lost the original art for King Ottokar's Sceptre
; he didn't have it upon his return to Brussels several weeks later, after the surrender of the Belgian Army and the King's call on his subjects to go back to work.
It never returned to him, and somewhere around 1979 it found its way into the hands of dealers, who sold it on at ridiculous prices!
I think that's evidence enough that he didn't get inspiration for some of his characters from the plymouth brethren in Paris neither.
Ah - that's really a different matter! :-)
We can't eliminate the possibilty that Hergé knew and used a member of the congregation in a completely different context!
All we can say is that Hergé didn't work in Paris, and didn't base the Detectives on anyone he knew or met there.
We cannot rule out that someone who was or became a member of the Plymouth Brethren congregation in Paris knew Hergé in Brussels, or worked with him there. There's nothing to say that someone already identified as one of the real-life figures wasn't in the Brethren, and from Paris.
However, it's an absolutely up hill struggle to work at the identification from that direction, as there are just so many figures in the books, any one of whom Hergé might have based on faces he knew.
I wasn't trying to put you off, just to point out that there was no quick solution to the question; until you can source a name of the model or models, a time-frame, or even an album in which they might appear, we won't be able to start drawing the net in and getting closer to an identification.