Let’s add a Y-Hanger to a chest harness, in this case a Shinju. Run the bight of the new upline under both straps.

Pull it far enough through that you have some with which work.

Now pull the part of the rope between the two straps up away from the body to form a secondary bight.

Hook the carabiner through the bight…

…then around the part of the rope between the two straps…

…like this…

…then around the tail.

Make sure the carabiner is fully closed.

Add an Overhand Knot or Half Hitch to lock the lines of the hanger.

Make sure it is seated firmly.

This line is now ready to be run up to the hard point.