<font color='#FF00FF'>Interesting reads.
When diving with a single & pony, which is on, I tell my buddy to to take the regulator closest to them. So they have a choice of 2 on the primary reg & 1 on the pony.
Once the out of air buddy has got air & is calmer, the reg with the most air can be passed to them.
Just make sure that you practice out of air situations regulary on your dives, it will make you more comfortable and ready if ever required.
Practice under water is never dive time wasted.