Thanks for your thoughts and suggestion. The feeding tube length was what we are trying to couple to extend it.
I may not have copied the correct size from the information of the tubing. From what I understand the diameter is a number 20 french, which is the inside diameter approximately 3/16ths of an inch. My partner being mechanical minded already thought of couplings similar to your suggestion. We were hoping to find a more medically approved coupler designed specifically for the peg tube.