Hi there! I created a site using Atahualpa theme, however, I haven't created a child theme and made changes to base code. I'm isung multi site network and I'll need to clone this site several times. It turns out that I'm afraid of upgrading to latest version and lose the changes I and if I don't, I am afraid that someday there may be incompatibilities with some plugins, for example.
I read you said that it's not necessary to use child theme with atahualpa...but can I update it without losing work already done?
Thank you

You WILL lose changes you have made to any theme files if you upgrade. The theme settings however are stored in the database so they will be preserved in an upgrade. The items you would still have to deal with are the logo, header images, favicon files etc. that you have uploaded to a theme folder. They would need to be added to the newly created theme folders after an upgrade.

I use the manual upgrade method as described here.

As always be sure and make a backup of your site before upgrading.