I appreciate if future enhancement can take an option where you can add node relation to EXISTING in X, Y & Z direction. This option is available in some other software like ETABS where you just input X,Y &Z coordinate and click existing node and can easily add node relative to other.
Thank you for posting this idea. I can however confirm that the functionality already exists. Simply select your base nodes, then press CTRL+C then CTRL+V (i.e. copy and paste), you then get a dialog to let you paste them relative to their original locations thus:-