I am applying to several US grad schools for a PhD in Math for fall 2023. After my schooling I got admitted to a prestigious research institute (say X) in my country for a BS with double honors. I had several financial, health and other family issues back then which affected my mental health and thus my performance in that program. Eventually I failed to fulfil the criteria for promotion and decided to discontinue the program after a year and a half. I did not receive any official transcripts or degrees from this institution. After that I completed a BS, MA and MS degrees in math. Due to those persistent issues, I did not do well in my BS and MA programs but since things have improved dramatically recently, I have done very well in my MS course, my GRE and TOEFL exams and have five strong letters of recommendation from my MS professors.
Now, I mentioned about X in the academic history section, the coursework list and my SOP/PS for some of my applications and one grad school is demanding marksheets of all work done at X. I have contacted X to see if they can provide me with the necessary documents and am yet to hear from them. I have a few options that I can choose from for my future applications, and I need some help figuring out which is the best one:
If X gives me an official statement that they cannot provide marksheets since they don't keep records of students who discontinue a program (unlikely), then I can keep mentioning X in all those three places in the application form and provide the grad schools the statement that X cannot provide marksheets. This would allow me to have the benefits of saying that I studied at a prestigious institute for a year and a half without the drawbacks of showing my poor marks. I can't possibly request X to provide me with the statement instead of the marksheets if they have the records, can I?
If X gives me the partial marksheets then I could:
a) Do the same as in 1 but suffer the consequences of showing my poor marks and try to explain the reasons in my SOP. However, most of the good schools have strict word limits and it's difficult to explain this complex issue there with short, generic statements so I'm not sure if they'd understand.
b) Not mention X anywhere in my application since I already have a BS from another place to satisfy their eligibility requirement for a bachelor's degree. But would this be considered unethical since I'm technically not sharing my full academic history? Most of the application forms ask for "degree-granting" institutions and since I didn't receive a degree here, I could choose not to mention X. I could similarly choose to omit any mentions of X from the coursework list and SOP.
Kindly help me figure out the best course of action here. Several of my deadlines are on December 15, so I need to decide before that.