I wonder about the DOF of the CMC2 compared to the CMC-1 lens

I have a MFT camera (Olympus) in a Nauticam housing. When I dive with macrolens (mostly a 45mm) I add a CMC-1 on a flip adapter. However, I don't like the combination, for me the DOF is to narrow. As I am also not very interested in supermacro, I am thinking about buying a CMC-2. Jet I doubt if I will be disappointed with the DOF of that wetlens as well.

Can someone tell more about the DOF improvement after moving to a CMC-2?

Depth of field is a function of magnification, if you reduce the magnification on the sensor you get more depth of field at constant f-stop. There are special cases with wet lenses but shouldn't apply to a simple diopter. Bearing in mind of course that the depth of field is already razor thin at less than 1mm with the bare lens at 1:1 magnification.