Having just found this forum and looked at a couple of old threads, here's my pennyworth as far as my own investigations indicate!
Deboneetbeau was indeed the proprietor of Louis Lot before Barat. However, I saw a Deboneetbeau flute (named as such - not Louis Lot) for sale recently. Maybe he made a few after leaving LL or maybe he had a son. It should be quite easy to find out.
Indeed Louis Lot was sold to SML Marigaux after Mme Chambille's death in 1951 or 1952. If you look at Gofer Joe's web site you'll see he has a 1950 Marigaux which doesn't sound very wonderful. I have a 1955 Marigaux which is excellent and another from 1956 which is not quite as good as the 1955 one. The last master craftsman at LL was Martial Lefevre. It isn't clear whether he went to SML. However, he had a son Jacques who was indeed at Marigaux in the mid 1950s but it isn't clear if he started under his dad at LL. However, Jacques later set up his own business as Jack Leff.
My two Marigaux are identical but differ from Gofer Joe's in several respects. Mine are open hole (his are covered). Mine have soldered tone holes (his are drawn). Ine has additional adjusting screws. It would seem that the takeover of LL resulted in various changes to the design of the Marigaux.
For some years following acqusition of LL, it seems that SML continued to make plated flutes under the Louis Lot name whilst the Marigauxs were all solid silver.
I have visited Marigaux in Paris and emailed them to fill in the gaps and confirm the saga - but they're totally unhelpful.
