Is there any way to sync up the volume of both the handsfreelink and stereo. It will be a question of time before I blow out my eardrums when I try to make call while listening to the stereo.

 

The volumes are independent and recall previous settings, so you should be able to adjust each to a comfortable level and leave them there.
The HFL volume can only be adjusted when activated (i.e. while on a call)-- adjust that to a comfortable level and hang up. Nothing you do with the stereo volume will affect the HFL volume, so a call through the HFL will be at the previously-set volume, and vice-versa for stereo volume.