The clone for Project or Solution is one option, though it can accidentally be left enabled and cause confusion.

The simplest answer is to use the Special Folders which are simply folders on disk at the same level as the solution.
https://www.visualmicro.com/page/Special-Folders-and-Portability.aspx

For your use case I would expect the Arduino-Solution/Libraries folder to be the simplest:

e.g. If you have your SLN file as below:
YourSolutionFolder\YourSolution.sln

You can create the folder:
YourSolutionFolder\Arduino-Solution\Libraries

And copy in the library you want to edit and use.  Visual Micro will automatically pick this up after running vMicro > General > Rescan Toolchains and Libraries. or restarting Visual Studio.

If you restart Visual Studio, and run Build > Clean Solution as well this should resolve the issue.

Apologies, the folders are case sensitive and must be in lowercase to work as expected (my fault).

Can you close VS, then rename the folders to arduino-solution\libraries, and then try reopening and clean/build the project again?

Thanks for the update.

If you could send us the whole solution ZIP'd (the .vs folder at the solution level can be excluded).

Also please send the build output as a text file, with the options set shown at the top of the page.

I think I've found the problem Simon, I was putting the contents of the library folder into your special folders, not the folder and contents itself.  So now the compilation completes without errors and from the extract from the build output below I assume that the TFT_sSPI library, located in the solution folder, is being used?

Using library TFT_eSPI version 2.5.43 by Bodmer in folder "E: Users Steven Documents GitHub Visual_Micro ESP32 ESP32LCDRound240x240Eyes arduino-solution libraries TFT_eSPI"

Thanks for your help and support Simon.  I've only just started using VM but I also use PlatformIO, STM32CubeIDE et cetera and like those IDEs I have run into a number of issues, some I worked out myself, some from Internet searches and others with your help.  I usually generate a number of text files with the problem and solution, as an aide memoir and I'm going to create one for this issue.  I'll send you them so you can see from a newbie user's perspective the kind of issues that others may come across.

Attached zip file includes my problem-resolution notes and some URLs I found useful.

I also added a note about a possible mistake in the user guide, not sure if you have seen it, but it's here: https://www.visualmicro.com/forums/YaBB.pl?num=1723375114