Hi all, seem that summer has slowed down this forum activity and I thought to break the silence.
As we are celebrating 150th anniversary of the birth of the Sibelius, I dig interweb a while and found this.
Following link takes you to youtube where can be found really nice piece of Sibelius for piano and harmonium.
Found from books following info that early 1887 Sibelius family stayed in city of Loviisa where they spent time with Sucksdorff family and they had both piano and harmonium in their house. It is thought that during this visit Sibelius composed this piece for this "unusual combination" of instruments and it is dedicated to Betty Sucksdorff.
Later Sibelius also composed longer piece Quartet in G minor, for violin, cello, piano and harmonium that is also dedicated to Betty.
Both pieces can be found from Sibelius - Complete Piano Quartets CD.
Best Regards Jaakko