Site Title and Logo

I am keen to have on my site identity a logo, a site title and a tagline.
At present adding the log disables the site title but not the tagline.
I already have a child theme as you recommended this to resolve another issue in functions but I am sort of reluctant to change the child theme as you recommended to another user (https://www.ads-software.com/support/topic/display-logo-and-site-title/) as I fear I might then lose any improvements you add to the core theme.
Is there any other way to get logo, title and tagline showing?

The page I need help with: [log in to see the link]