Generally speaking, coats of arms do NOT belong to families of the same surname. Coats of Arms are granted to a specific person and are normally inherited only by his bloodline descendants bearing the same surname. Otherwise, what would be the use of having over 500 different coats of arms registered in the surname of Smith (for instance)? There are literally thousands of people who bear the name of John Smith, but only the one John Smith will have a passport or driving licence that belongs to him alone.
Just because you happen to bear a specific surname, it does not follow that arms registered in that surname can legitimately be used by you or your immediate family.
I suggest that you have a look at the information that appears in Francois Velde's web-site at http://www.heraldica.org/questions.htm
for a fuller explanation.