Ive been wondering,is there a way to change the race of a companion to a custom dragbosy race?like change raul to chakan?

There is, what you do is go into the geck, and open the race .esp as your active file. Then find and open the preset for Raul, after that click the drop down arrow next to race and then pick the race. After that look down in the corner at template data and click the drop down arrow for actorbase, and then select the race preset for your custom race, and then put a check mark in the box that says 'use model/animation' click ok, then save the .esp and your done.

This method is how I got Veronica to use the Miranda Lawson race made by Isquall

Its not hard but there's a lot of steps.

Most custom races used a merged mouth that is one piece instead of several, you assign that to the 'mouth' slot and then use an 'empty' nif like Vacuus.nif (which is usually included in mod races) to fill the other mouth slots. You can also use them for things like eyelashes.

And don't forget to create an eye type in Characters > Eyes... at the top. This is critical for properly displaying the eye textures of a custom race.