Adding extra info to employees

Hello all,

I was wondering how I can add extra information to my employees page.
I played around with the extra fields plugin and I was able to add more info to the page.
However, I did this in the fp-employees.php file itself but an update to the theme will remove this customization.

I read that you have to either create a plugin that sideloads and adapts the behaviour of the plugin or work with the hooks.
Is there any good documentation on how I can implement this for fp-employees?

Thanks in advance

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