bernd2700

Dear "saralandry",
I am new to this forum since today (15.1.2021) and I have seen your question below. Did you solve the topic already?
Coefficient "c2" is for singlebit, what you have, usually also named as "quantizer" gain (more precisely the "quantizerdac" gain since "gain" is unitless", often referred as to "kq" or "k", check Schreier). And this also has to be modelled if you want a correct model e.g. in Simulink. How to calculate it: Check Schreier, Yellow Book, p. 144.
Of course a different kq will shift the STF, too. Make a simple Matlab feedback model, so do a la:
STF = Forward / ( 1 + Forward * Return )
whereas the "Forward" includes the multiplication of "kq".
The fullscale, input referred, is also what is the fullscale of the DAC multiplied by any gain blocks. E.g. if the gain blocks from the feedback (=DAC) are 1 and also the input gain blocks are 1, and the DAC FullScale (FS) is e.g. 3V, then also your inputreferred FS is _in the average_ also 3V. If there is an additional gain block from the feedback, e.g. factor 2, then your inputreferred FS is 6V.
Got it?
Nice greetings, bernd2700
