As a (temporary) workaround you can use a text editor to copy & paste parts of the graphics between schematic symbols. I would probably:
1). In the Symbol editor, make a copy of an existing symbol.
2). Move the part you want copyied for example 100mm to the right, (and/or delete unwanted stuff)
3). Save that symbol.
4). Mess around with a text editor.
5). Verify the graphics has arrived at it’s destination.
6). Delete the copy you made in step 1.
Also, a few years ago I had a little dab in Python, and in an afternoon I got as far as creating a KiCad schematic library with some 20+ connector symbols from a python script. If a scripting approach is usable for you then have a look at: