@tanguatlay,
Quote:I know Jeremy's sister who used to go to the same school as me/I.
Which pronoun should I use?
The language/grammar structure that the speakers of any language use is not dependent on silly ironclad errant grammar "rules", Ms Tan.
Setanta has opted to give you false information based on his not very extensive knowledge of the English language.
For him to tell you that you should use 'I' in this situation, which seems to be an informal one, is silly because it could make you sound like an pompous idiot.