Singing and Supporting its Foundation

Hello Mike,
I was wondering if you can help.
Is it true to say that for singing we need to keep the diaphragm expanded, to resist its temptation to rise back up into its natural position for control of the air?
Is this achieved by the following exercise:

Keeping the lower ribs expanded and with hands on waist coughing gently 2 times and you should feel an outward pulse against your fingertips. A gentle but firm outward pressure.

This support should be established just prior to the sound and maintain it to the end of the vocal sound.

From Mike:

Not happy with the cough. Also, not so much focus on the waist as many have different views of the waist. Try more in the soft area above the pelvis and below the ribs.  Push out with the belly muscles as you speak or sing or do your vocal exercises.  Recommended Program