@DaveHR Yes, QRZ lookups require a premium subscription to give you Grid Square info via query. I thought you were asking about your own grid square in HAMRS, which is not pulled from QRZ.
I understand what you are describing with respect to other users looking up your QTH info to populate their own QSO logs. They will always get your address as associated with the log. Even if you change it temporarily when you’re portable, and change it back later, the other ops will get your QTH data that happens to be posted at the time they look it up. I’m not sure there is a reasonable solution for that.
However, when they upload their logs to QRZ, those QSOs will be matched with the location data you entered for that specific QSO. Your QSO location data does NOT need to match your address on record.
After I log a bunch of portable contacts, I go into the QRZ logbook settings and change the state, county, city, and grid square. Then I import my log (for instance, a park activation log from HAMRS) into QRZ. Then I change the logbook settings again to show my home QTH. This approach ensures my QSOs accurately show where I was at the time the QSO occurred, and allows other QRZ users seeking award credit to get that credit appropriately.
My home QTH, associated with my FCC record and my QRZ page, is in Centerville, OH, Warren County, EM79wn.
You’ll note that for my activation of Hueston Woods State Park today, in Preble County, OH, EM79on, I changed my logbook settings as follows:
All QSOs imported with those settings assume the temporary location data. Here is one of those QSOs:
So the QSOs now match within QRZ, and contain accurate QTH data, but the other op’s personal log may not include my correct QTH if they used the lookup service to retrieve it,