I suspect that if significant deception is detected, an acceptance would be rescinded. Moreover, word of such things “get around”, and reapplying the following year might not be welcomed.
Yes, but the parents with their lifetime of lying ways usually have little expertise on what children are like, other than their own.
There was a young applicant last year who discovered after a dismaying M10 that their parent had replaced their application essay on Gateway. If I recall correctly, the only acceptance the kid had was the unaltered application to a “safety” school, which the parents deemed not good enough for their child to attend.
So sometimes the system works.