My family has been invited to a graduation party by some Hindu coworkers at their Hindu temple. Would it be appropriate for my Catholic family to attend?
A graduation party sounds like a secular event, so there would be no problem attending the party. If there were religious services held in conjunction with the party, you should attend the services as a guest and not a worshiper. Basic etiquette for a guest at religious services of faiths not his own is to stand when the congregation stands but otherwise to sit quietly and observe. If this were a Christian congregation, you would refrain from receiving communion.