Quick-fire questions
Why does Photoshop
Elements 12 crash when opened?
> If you see a crash report (look in Console), check if it lists a signing or certificate error, indicating its certificate has been revoked.
Otherwise see if you’ve installed anything recently that could cause this. Contacting Adobe support might not help, as Photoshop Elements 12 is no longer supported.
Can any app add new files to an existing Zip?
> This is a trick that has been available in some older PC compression apps, but as far as we know has never been offered in a Mac app. It’s not efficient, and can give rise to problems, so it’s better to decompress the existing archive, add the files, and recompress them.