<1> Open the montage you want to apply a pose overlay.

<2> add montage pose overlay anim notify in details pannel we can set a montage pose and a gameplay tag that alows you to create your custom conditions (if the pose should be applied)

<3> add another notify when pose should reset

This will remove Pose Overlay from the montage. You must add this to reset if you previously used the notify (correct settings are in the relevant screenshot).