Concatenate the SUBJECT NAME in the average results with the DYANAMIC LETTER GRADE

Hello all
Greetings!
I have attached a workbook here containing sample data and clear explanation of what I need.
This is what I want to achieve:

I need an Excel formula/VBA Code that will do the following:
1: Concatenate the SUBJECT NAME in the average results with the DYANAMIC LETTER GRADE which will change automatically as average marks changes for each subject as per the criteria given in column AO and AP.. Refer to the combined results column in the attached workbook for the output I want; then:
2: If the student does not take any of the above subjects then it should not concatenate that particular subject with its marks, it should leave it blank and proceed to the next subject; refer to the second student in the attached sheet (check the combined result for the second students, that's the output I want).

I will highly appreciate for your help!

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