Skinny puppy
 

I think I posted this question in the wrong area so I thought I would repost it here.
Hi all,
I am looking at buying a Biewer, a female. She seems healthy but she is skinny. Everything about her and the breeder is exactly what you would want.
The breeder lives in a really nice home. The dogs were raised in the home. She only has the one bitch. The stud is beautiful but she doesn't own him. The Breeder has owns the bitch's father.
There were three puppies in the litter, 2 males and 1 female. They are 6 months old now, the female weighs 2 lb 14 oz. She will probably top out at 3.5 or 4 lbs. Her brother weights about 8 lbs now. He is going to be big. The breeder told me there are bigger dogs in the mother line but the mom is 5 lbs and the dad is 4.5 lbs. When I petted the bitch's father he was kind of thin too.
Really my only red flag is that this puppy is skinny. I am thinking that she is probably small because the other dogs get more of the food. The breeder offers a 1 year health guarantee. She is up to date on all her shots. Genetic testing has been done.
All I can think to do is insist on a vet check with me present before the final payment. Other than that she is gorgeous.
Any thoughts?
Thx

Has pup been dewormed and/or fecals done?

Most contracts I've seen require that you take the dog to get a vet check within 48 hours you receive him/her- does your contract not have this?

What does the breeder say about the weight of the male dog and the puppy- does she feel they are too skinny?

Many people are not used to seeing very healthy, lean dogs and may feel a dog is too skinny that is not- or maybe the breeder has some explanation of the weight.

The breeder said that she was healthy and that leanness ran in her bloodlines. She also said that the puppy had had all her vet checks and her vet never said anything about the puppy being too skinny.
I am hoping she is just a naturally lean dog. My last Yorkie died of PLE (protein losing enteropathy) their bodies can absorb the protein they need to stay alive. They basically starve to death. So I know what a skinny dog looks like.
While the puppy feels thin she doesn't stumble from weakness or lay around. When I visited her she was playing with her brother and even though her brother is twice as big she is, she is the more dominate dog.