Yes Bella was like Murphy, she would growl if you picked her up, so we would hold her until she lay quietly and then put her down when she was quiet. It works like a dream. She also was "picking" on my eldest daughter who was 11, the vet said it was because she saw her as her equal so we had to teach Bec to "dominate" and Bella soon learned that she was at the bottom of the pack. Sound awful, but its how it has to be, IMO.
I took her to the vet on Monday for jabs and she did it to the vet, he said NO sharply and she soon got the message. Then licked his face to say sorry 
I disagree with this method strongly too I'm afraid. I've had two cocker puppies with young children and IMO this is NOT the correct way to establish a good trusting relationship between the children and the puppy.
Puppies and children generally don't work. Children excite puppies and are not capable of being consistent or putting up with the pain of puppy biting. I was given some seriously good advice by a dog behaviourist (not a vet that's been watching too much TV and never actually studied dog behaviour). If you have problems with your pup and your young child keep them separate until the pup has grown out of the biting stage. It's as simple as that. It's what I had to do with my second pup and he's now great with kids. He was kept separate in the kitchen with use of a baby gate until about 8 months old when he grew out of puppy biting. He was allowed supervised play with my 5 yr old son but when he got too excitable he was quietly put in his area to cool off. It seems like a long time and is a little inconvenient, but it's more than worth it to establish a firm family friend that you can trust and avoid any potential situations that could have long term effects on pup or child.
Trying to get a child to 'dominate' a dog is just asking for trouble - the child doesn't have the experience, knowledge or skills to do this and all you are doing is teaching a child to bully a dog rather than respect it, which is SO dangerous for both dog and child. I'm appalled that this was even suggested by a vet and just highlights again that it's sadly very rarely that vets give good behavioural advice.
Your pup will grow out of his current behaviour but it needs managing, not dominating - would you 'dominate' a 6 month old baby? Puppies need nurturing and time to learn what is acceptable - rewarding them for good behaviour will teach your pup how to fit into your family. Bullying it will teach it how to enter into conflict or worse.
Also with regard to the growling, as others have said she is learning how to communicate and also she will play growl. If she doesn't like being held don't force her.. hold her when she's comfortable with it and make it a fun pleasurable brief experience for her then she is more likely to want to do it again.
You need to gentle encourage a good relationship with a dog - as you do a child. It's not about showing them you are in charge it's about them finding a way to fit into your family that's enjoyable for them and you.
To give you some reassurance, my current cocker was an absolutely horrendous puppy he used to attack and bite even if I just said 'No' to him up until the age of 8 months. His reaction to fear or things he didn't like was to become aggressive and bite (on top of normal puppy biting and teething). He learnt how to behave acceptably because everytime he was biting too much or getting out of hand he was quietly put in a separate place from us and over the months he learnt that if he behaved how we wanted him to he got rewarded with attention and time from us. We now have a VERY sweet 2 yr old dog that's trustworthy with children, loves to please us because it makes him feel good and trusts us too which is SO important in a family dog. It's a good 'relationship' and we don't need to 'dominate' him
Lots of luck you do have a few months of getting your head down and managing her which is normal for all puppies, but rest assured that your pups behavior at this age is completely normal and if managed correctly and kindly you will have a lovely adult dog.
Hannah x
