Upgrade advice and suggestions please

Hi,

I have inherited a shop using the Shopper Theme V6.3 and want to upgrade to the latest version as cleanly as possible. I’ve downloaded ST.zip and tried to add it as a new theme via the WP admin screens. Unsurprisingly, it tells me that ST already exists.

If I rename the ST theme directory and install it, it wants me to set it up from scratch, of course. I don’t want to do that!

How can I upgrade from 6.3 without having to set everything up again? Is it as simple as just overwriting the current ST theme directory with the new one?

Another site I’ve inherited has the Pink child theme as well. Is there anything special I need to do to deal with that, please?

Of course, I’ve searched the forums, but I can’t find the needle I’m looking for in that particular haystack!

Many thanks, Laurie.