I have Hirculine's Tabaxi Companions, [male/female] they have no voice. Are there any voice plugins that give voice to silent partners? I also have "3 Chocolate Elves CM Partners". They have the vanilla Redguard voice. What is the procedure to link a companion mod to the vanilla voice file/folders?

When you make a race, set them to use vanilla races' voice. However, some vanilla races share voice data with other(like Imperial female and Breton female), making custom race to use wrong voice sets can make him/her silent.

"set them to use vanilla races' voice." How, what is the procedure?

"making custom race" I am not making a custom race. I want to either find a voice mod or a way to link a silent cm partner to an existing voice like the above Chocolate Elves which uses the Redguard voice files.

Open up the CS and take a look in the Race menu. Should be fairly straightforward to figure out.