Just to clarify, the BHT-1 wasn't designed by Saab engineers, it began as a student project at the Kungliga Tekniska Högskolan (Royal Technical University) in Stockholm. The BHT acronym stood for three KTH students - Bratt, Hilfing, and Törnblom. Matthew has already mentioned Erik Bratt. I'm not sure what becomes of Karl-Erik Hilfing (although his later patents are non-aviation related). Björn Törnblom worked under Bo Lundberg on the FFVS J 22, later moving on to SAS.
Skandinaviska Aero AB (SAA) and Svenska Aeroplanaktiebolaget (SAAB) weren't the same thing. SAA was a small 'airline' which was mostly involved in contracted target-towing for the Flygvapnet. SAA had begun as Björkvallsflyg back in 1931. Founder Kurt Björkvall - the Swedish aviation pioneer - was killed in a 1940 and Björkvallsflyg was renamed as Skandinaviska Aero. [1] SAA lasted until 1948 when it was bought out by the SAS (Scandinavian Airlines System) consortium.
The BHT-2 was indeed a two-seat derivative of the original BHT-1. But, just to be clear, it remained unbuilt.
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[1] Some sources state that BHT-1 contruction began under the Björkvallsflyg banner ... which seems improbable.