Z-Depth animation with COA tools

Hi,
I am animating a game character using Cut out animations plugin, but I’ve reached the point where I need to change Z-depth of one sprite during the action animation, but I can’t figure out how. Any ideas?

Here is the character for better description:

I need to move those big “claws” in front when he attacks. But when I tried to frame the Z-Depth property it prompted me to “Create new animation collection” but I have no idea about that either.

Thx for any help or suggestions,
Red stripe