As these are members of the "Baltenregiment" I think the tunics are of Russian origin, as the peaked caps are without doubt.
The "Baltenregiment" served with the Estonian troops between 1918 and 1920 in the war against the Red Army.
It consisted mainly of Baltic-German students of the University Dorpat (now Tartu) and of the Riga Polytechnic and additionally some
German soldiers of the former German occupation forces.
Commander of the "Baltenregiment was the Russian colonel Constantin Weiß, who later served as colonel in the Estonian army.