Stillach
At its confluence with the Breitach and the Trettach in Oberstdorf , the Iller is formed . 
<triplet> Breitach <subj> Iller <obj> mouth of the watercourse <triplet> Trettach <subj> Iller <obj> mouth of the watercourse <triplet> Iller <subj> Breitach <obj> tributary <subj> Trettach <obj> tributary