I have problem with selecting in sculpting. It only wants to sculpt the last object I selected in Object mode. Here only plane.010 is being sculpted and its mesh icon is highlighted, when I press double A, everything deselect but that triangle icon before Plane.010 name is still highlighted, and so when I select some another than again same problem but only with that Plane. If I select multiple, last one I selected is highlighted and being sculpted etc. What am I doing wrong?
The only way how you can do that (at the moment) is to actually join them togeher. Select all of them, the Shift-click on the one you want to be the center and press Ctrl+J. This way they are all one mesh and you can sculpt away. If you need them to be separate again at some point, go into Edit Mode, press P and select By Loose Parts.