look at what is detailed in your plan's T&C. i doubt that any specific statement against sharing will be explicitly defined.
tbh, mahirap i-police ito, apart from abnormal amount of data used. kung merong specific item about "fair use" sa unlimited plan mo, it could be cited as an indirect declaration (not to share).
basically, you're provided a service, e.g. 500 Mbps. kapag nag-share ka sa buong baranggay na may 500 people, eh di 1 Mbps each na lang kayo. note that this is not evenly split.
ang net effect sa ISP, mas madalas ay mapapansin lang kapag nagkaroon ng congestion sa node mo in their network. ito ang maaaring trigger para mapansin ang unusual usage. what i'm saying is kahit mag-spike ang data use, as long as it's not causing network issues, most providers wouldn't be concerned.
but then again, Terms & Conditions ang tatakbuhan mo:
ingat ka rin sa ganito... baka me kapitbahay kang "weird", at mayamaya kumakatok na pulis sa bahay mo dahil me inaccess na site o na-download na kung ano man.