After I upload my high school transcripts while applying, will the?
To me it sounds like you doctored the transcript you sent to university. Not a great idea. I have heard of people being caught for things like this 30 years later and fired / had their degree revoked (unlikely it will be that extreme, but who knows what attitudes to cheating will be in 30 years). But to answer your questions i would guess that it would be rare that if you were asked to send a transcript that they would go back to the original institution. Depending on where you are - some universities may have access to the school system and may be able to check automatically - but if they could do that, then I doubt they would have asked you to send one. Dont cheat, eventually you will get caught.