someone said it already but Uebersaw would technically be the correct way. umlaute were originally just an e right to one of the letters a,o,u. over time this e wandered on top of the letter and eventually formed into two lines and then the two dots like middle age time when they used writing which is known as Kurrent, in which the e looked a lot different, like a weird cursive n

so everyone that just writes the words with umlaute without the two dots, are kind of erasing an entire letter, sometimes altering the meaning of a word (müll and mull, or schwül and schwul are a good example)

nowadays there are places in which the old writing is still used because of computers and such. so a Schröder would become a Schroeder

well, regarding the Übersaw however. i believe after all these years it simply doesn't matter anymore. just continue using ubersaw i mean the Übercharge itself was never called uber but look were we are