Now I haven't thought of every circumstance or whether this may be a trick question - but I can think of two situations, one specific and the other very broad. #1 (Specific): T44S, R33E - SE Corner of Section 6, see L-1 RW Map (Boundary Survey) and the survey report I had to write about the missing corner (recorded in Hendry Co Public Records (PB 6, Pg 205). Thankfully we did not find/prove the GLO corner, but at this particular corner the GLO first came through and then the TIIF had Elliot come through - in this case, the corner falls within the Everglades Patent, so Elliot's position for the state corner should override the GLO position as the land was not considered "surveyed" when it was transferred from the USA to TIIF. #2 (Broad): Never. If you have a proven GLO corner - show it. A survey does not need to be black & white, hold something or not. You can show an option to hold other corners, and show what evidence supports that option and what evidence supports the other corner. I somewhat did this on the L-1 RW Map (Boundary Survey), I had options and chose to hold the State corner as I couldn't find any evidence to support an unproven GLO corner.