A String of Pearls

mm.
Eb:
11 - Iadd6
12 - Iadd6 bVII7 V7/IV
13 - IV IVmaj7 IV7

This excerpt is pretty tricky because of the chromaticisms especially in measure 12. Looking at the D7-Db7 is particularly interesting because, though the parallel fifths are diminished, it is kind of an awkward chord progression. The Eb7 chord in a tonic of Eb is also a bit jarring, though looking at the Ab chord (IV) in the next measure, it becomes clear that this Eb7 chord is functioning as a secondary domninant (V7/IV).