Thanks again Pichlo, especially while engaging in family time, much appreciated.

Sorry my description was a bit loose, I was hungover and shouldn't have been at the keyboard, I really tied myself in knots, but thanks to you, I now see why I wasn't succeeding where patching is concerned.

Yep, you're right and I see it now, a plain old RPM with a script for the hiding/renaming existing font files. I have yet to have a go at scripting, I'll look for some examples.

I realised around 3am this morning, that I can just install my new fonts to the existing sail-sans-pro folder and then hide/rename (as you've said) the existing .ttf files by placing a period at the beginning of the title.
Same for the files in the 'roboto' folder, add new fonts and then hide/rename the existing fonts.

Thanks again Pichlo, look forward to your response, as and when

Regards,