Problems with merging projects done using the app

Hello! Our experience is that the DJI unit varies its height when performing missions with a few minutes pause between them. I guess this might be because of varying GPS conditions, but the main concern is when trying to merge the different missions. They are put on different levers in the ray editor. I am having trouble getting then to join correctly. Do you have any tips on how to adjust the missions so that they are merged correctly ? (Manual tie points? Anyone else have experienced things like this?)

I have no experience with this, but I believe you should definitely have manual tie points or GCPs.

Yes, it looks like the GPS change some meters, but creating some manual tie points or using GCPs solve the problem.