Would the other Recorder 6 user be prepared to do at least some of the merging for you? If you used a rucksack to export recorders to them without observations they could import that and do the merging, although it would probably be worth trying to restrict the export to just the recorders they need. This would mean that when they export data to you, you would only get their recorders when they haven’t been able to merge them with one of yours. The same applies with locations. A single rucksack can be used to export multiple locations, people and documents. In an ideal world, record centres would use this mechanism to give their contributors the locations, people and documents they need before they started entering their data.

I think what you are proposing would work but it would be worth testing for unforeseen problems. The trouble is it would leave the other Recorder 6 user with the job of deleting their version of the recorders. If they didn’t do this there is always a chance that their version would be used when entering new observations which would mean them reappearing in your system when the new observations were exported to you. In the case of merging locations, it is worth removing as many attributes as possible from the one you are going to get rid of before doing the merge otherwise they get added to the one you are keeping.