I have a weird grading policy and am wondering if there are any options that can help me with it.

I haven't found any options that work, so a new feature? The ability to lock an individual score.

Here is the background rundown:
I have 1 grade book for all sections (3) of my Digital 3D Design class and use 1 Google Classroom for all of those sections as well.
I don’t create new grade books or GCs at the semester.
I allow students to “keep” their grade for the school year and let them work on old assignments as needed. So my grade book is setup as “Year”.
This works perfectly and has for many years.
The issue comes up when students take the option I give them of resetting their grade, essentially starting over at the semester. (Like the normal teachers do)
In the past, I have always just gone in a put NA in the Aeries grade book for the last semester assignments for those students and reentered that NA every time I imported grades from GC, as it would overwrite the NA with their grade from GC.

This year I thought I would try to save myself the time and hassle of having to enter NAs over and over again, each time I imported grades from GC.

Here is what I tried with no luck. I went into GC and marked the assignments as “Excused” for the specific students that are resetting their grade. When I import into Aeries, the grade still comes over and I have to enter NAs again.

Is there something I can do differently to make my dreams come true? Can we have a new feature allowing teachers to lock an individual score so it won't get over written with a GC import?