Find-grave is just like any other "online source", great for hints, poor as an actual source. Wrong attribution of markers to people, markers with incorrect dates as a lot of old ones are subject to memory and even "memorials" with no marker photos or anything else to back up it existence. People have to be first and it is hardly ever verified. This happens with government records as well. my dads VA marker is wrong, and they won't fix it. he was never a "Jr.", despite some records claiming it. they have his wrong discharge rank, and will not correct it. My grandfather went though life claiming his birthday was 2 years earlier, which also resulted in an incorrect marker, and hits rank is wrong given when he was actually discharged. Is why we look at multiple sources when we can, and dig hard.