Partial conditional formatting based on the colour of a cell

Is it possible to change the automatic formatting of a cell based on the colour of it?

What I have until now (will attach a partial copy of the file):

I have managed to enter formulae that one just has to change the year at the top of the page and it changes all the months and days in the remainder of the calendar. Weekends are grayed out.


My aim:
I would like the calendar to still as it does, change the dates based on the year appropriately including the leap years (as it does), but additionally ----> I would like the dates to have a,b,c,d,e,f,g,h after the days Mon-Fri consecutively over and over again - but IF i change the fill of the cell (any colour, or grey), for it to skip those days from the A-H cycle (aka weekends and random holidays).

I will attach a file with a partial of what I have and an example of what I would like. (labelled on the side)

If anyone could figure this out I would be unimaginably grateful as I think it MUST be necessary as it is possible to change the colour of the cell depending on the value, so it must be possible the other way? But whether it is possible for a part of the cell as well, I don't know. I will be forever in your debt! ;P How this debt will be repaid will be news to me however, other than that you will have a fellow player in the world who is just a little bit more intelligent thanks to you.