Let me offer some perspective, based on my experience having worked as Dean of MBA Admissions and now continuing to work closely with the top MBA programs through my participation in AIGAC (the Association of International Graduate Admissions Consultants).
1) In terms of how to submit your MBA Math transcripts to the schools, it is usually done in the transcripts section. if need be, you can always ask the school. Don't forget that one important part of
mitigating your subpar GPA is
the optional essay. You should absolutely still use the essay to explain your undergraduate performance and to point out how you are mitigating it, including MBA Math.
When it comes to compensating for a low GPA, a strong GMAT is always the first and most important thing - and you've done this, which is great. But going above and beyond by taking MBA Math shows even stronger self-awareness and commitment to demonstrating that you are ready to do what it takes to be well prepared for the academic rigor of an MBA program. It's an important and strong signal so good for you for recognizing it.
2) In terms of how favorably schools look at MBA Math, here is what you need to know. MBA Math is very well known to schools and it is a respected tool. It's now been around for well over a decade and many top schools used MBA Math in lieu of the GMAT/GRE during the pandemic (examples included MIT). Even post-pandemic, many schools will still consider MBA Math as evidence of academic preparedness for those who are seeking test waivers. In your case, it will be even more helpful because you already have a very strong GMAT. MBA Math is more a prep tool than a test. The same is true of HBS Online CORe (formerly HBX). Let's not forget that the way CORe became so popular is because HBS used to require it of some of their admitted students, even if they had very strong GMATs but were lacking quant and analytical coursework from undergrad. Even though HBS used to require it of only about 15% of the admitted students, they discovered that nearly half of the class would take it anyway - simply because they wanted to be well prepared.
In your case, with MBA Math, you are going above and beyond so to speak - and every little thing that can give you an edge is more than welcome.
If you want to talk about any of this further, you can schedule time for us to chat:
https://www.mymbapath.com/free-consultation