This is the code:
[HorizontalGroup("Fade")]
[Title("Fade In")]
[HideLabel]
public bool OverrideFadeIn;
[HorizontalGroup("Fade")]
[Title("Fade Out")]
[HideLabel]
public bool OverrideFadeOut;
[EnableIf(nameof(OverrideFadeIn), true)]
[TabGroup("Fade In")]
public bool FadeIn;
[EnableIf(nameof(OverrideFadeOut), true)]
[TabGroup("Fade Out")]
public bool FadeOut;
So enabling/disabling either of the overrides will cause both tabs to become visible/invisible.

This is the code:
So enabling/disabling either of the overrides will cause both tabs to become visible/invisible.