It has already been establishedbeen established that Ashkenazim generally stand for Kaddish, while Sephardim sit unless they were already standing. (That said, I have observed Sephardim who davka sit for Kaddish.)
What should an Ashkenazi do in a Sephardi shul? Should one davka stand? On the other extreme, is it even permissible to go against the minhag hamakom of sitting? Conversely, should a Sephardi stand or sit for Kaddish when praying at an Ashkenazi shul?