I was just wondering if it was possible to change the projection of only certain objects in a shapefile, while the others remain the same. I have to insert points onto a map, and some of them are in a projection called MTM 10, while others are in MTM 13. In order to get the points into the shapefile I'm using, I have to copy and paste them from an imported AutoCAD drawing. The points are supposed to be in the same shapefile, but everytime I change the projection, they all move. Is there a way to get around this and only change the projection of a few points?
you should use the merge tool (or the append tool) to copy your points from one dataset to the other dataset. Launched from ArcGIS, the selection will be honored + this will reproject on the fly. Your points are probably moving because their projection was not defined. This can be done using the define tool. At the end, only one coordinate system is possible per shapefile.