The first performance, a private concert a Durand’s, the publisher, was played by a chromatic harpist(I think her name was something like Suzanne Dalie), with Darius Milhaud playing viola. I don’t know who the flutist was. Debussy probably received a commission from Pleyel to write the trio sonata, but he clearly and loudly stated repeatedly that he wanted his music to be played on an Erard. He didn’t say pedal harp, he said Erard. That’s why, a few months later, when Debussy heard that a young wizbang harpist named Pierre Jamet was working on the piece, he asked that trio to play the work for him, and then asked them to perform it at a public concert that Debussy had organized for the French Red Cross.