Yes, another cadenza

I am almost done writing down the second movement of Piano Sonata in C minor by Mozart. But there are 2 cadenzas that I don't understand how to write down. I can do long tuplets no problem and I used this method to write down 3 cadenzas before in Musescore(and these cadenzas are in the same sonata, same movement even). But those 3 cadenzas had eighth rests as a reference value in the staff above or below. These 2 cadenzas that I haven't written down, don't have any rests as a reference value.

Here is the first of the cadenzas(for reference, the key signature is 3 flats here and it is the second movement of the sonata):

How am I supposed to get that across in Musescore? I mean the cadenza starting after the first set of sixteenths and ending before the rest of the sixteenths? Do I just add a 9/8 time signature around here to get an eighth rest for reference as the length of the cadenza and then make the time signature and eighth rest invisible? Or is there a different way to get across the cadenza without any overlapping with the sixteenths? I am using a quarter note tempo marking.