Often users want to take a feature or layout from one of our themes and include it another theme or add a new feature to an older version of the same theme.
While these types of changes may be possible, adding in new features requires extensive development work to the theme's code. Our support team is unable to assist with such tasks and we don't have any guides on how to do this, unfortunately.
Combining theme files is likely to be very complex, costly and time consuming, so if you really need a feature in one version, you're likely better off upgrading rather than trying to customize the code.
If you're unable to upgrade your theme, you can always reach out to us with a feature request as we're always happy hear suggestions from merchants!