In n1, which shifts the typical Ländler key of D major up expressively to Eb, the subdominant embellishment in bar 1 is reinforced in the left hand, and in the second strain a very characteristic use of ^6 appears, as the harmony flirts with an outright V9. (Recall that you can click on the thumbnail to see the original size image.)
In n2, probably meant as the trio for n1, ^6 is offered very directly as a rising melodic embellishment in the first strain.
In n3, the play of ^5 and ^6 generates a simple motif -- the pairing of ^3 and ^5, the latter figured with ^6, should seem familiar from D779n13. In the second strain, the subdominant harmony suggested in n1 comes into full bloom, and we also hear the simple ^6 embellishment above I.
In n4, ^6 is an emphatic leap that announces the significance of the upper octave -- the strain closes on Db6, not Db5.
In n5, the alternate harmonization, with vi, is prominent, again followed by a characteristic embellishment, the V9. In the second strain, the V9 with its ^6 is given a very direct violinistic treatment, and the ending might well have gone differently -- see the alternate cadence below the score.
In n7, ^6 is buried in a trill on ^5, but in the second strain ^6 is again harmonized. The strong pairing of ^5 over ^3 with descending cadence motions (^4 over ^2, and finally (^3 over?) ^1) strongly implies ^3 as the alternate ending shows. I have written about this formation in the essay Complex upper-voice cadential figures in traditional tonal music published on the Texas Scholar Works platform: link to essay.
