allergic reactions

Hi, I have a mini dachshund, Cricket, 12lbs, 2 years old, dabble piebald. Today she went to vet for booster vaccines. The vet didn't want to give her every booster at one time, I.e rabies, 5 in one, kennel cough because she is under 15 lbs. I am an experience dog owner and have never been told...