This is what I meant. The senior line ended with barons in France (there was an even more senior French line that was never ennobled--I think). I know who Bernadotte was; he was a younger son of his biological father. His older brother's line continued in France until about fifty years ago.I don't know what you are talking about re the Bernadotte dynasty which has only reigned for 201 years.
The first Bernadotte was Charles XIV John, a totally unrelated to royalty marshal of France who was adopted by King Charles XIII. Charles XIV John's son was Oscar I, whose oldest son Charles XV was survived only by a daughter, and so his younger brother Oscar II became king. Oscar II's oldest son became King Gustaf V whose oldest son became King Gustav VI Adolf whose oldest son died before him but left an oldest son who became the present King Carl XVI Gustaf. Oscar Ii is the only Bernadotte king of Sweden who was a member of a cadet branch.
Possibly you were thinking about earlier Swedish dynasties.