I have removed a face inside one of my meshes, and now I'm trying to create a new one but based on 2 vertices from another mesh. In my tutorial it fills if with "F" key and creates new "quad", but at me it fills whole all area, not just 4 vertices. May be the reason is that I have a newer Blender version 2.81 while tut version is 2.79(smth). So I can't get a new fill with quad (pictures added). What am I doing wrong or not getting here? Thank you in advance.
You can't have vertices, edges or faces across different objects. Different objects need to be joined first. Select both objects and press Ctrl+J
In case you forgot to "join" mashes here is a useful link on how to do it Thanks!