Advanced Custom Fields is great but sometimes, especially when re-using field groups across templates, the admin area can get a little overwhelming. Tabs help but not when you’re using multiple field groups. To get around this I used to use this plugin for merging ACF tabs. It worked very well but hasn’t been updated in around 2 years and therefore doesn’t work at all on the new versions of ACF.
I needed this functionality yesterday for a theme I was working on and so I decided to adapt the code to work with the new versions of ACF.
This has only been tested on ACF5 so may be a little off on the late 4.x versions.
UPDATE: This is now available as a plugin on WordPress.org at https://wordpress.org/plugins/acf-tab-merge/