I have mated two cylindrical faces from the two parts, the result came looks like this:

As you can see, the two cyllindrical faces mated are the inside of the largest curve in the blue object and the main cylinder of the bottle object.

Then I tried using the distance mate, but it will only allow me to set the distance in the y-axis, and not z-axis (the measure shown in the picture). Obviously, since the two faces are already concentric, moving the part up and down will not work... so how can I change the distance shown in the picture?

Thanks for reading!