Adopting a Second Rescue Puppy

Question
My daughter and son-in-law rescued a half Lab/half Shar-Pei "special needs" pup a month ago.  This baby is a highly intelligent, very playful and utterly affectionate four-month-old.  Her medical issues have been taken care of, except for an upcoming check-up with a canine opthalmologist. They would like to adopt another rescue puppy, so the two can be playmates.

Question:

Today at a shelter, a volunteer adoption counselor strongly advised them until Puppy #1 is a year old.  They were told that bringing a new pup into the home now would cause the two dogs to form their own "pack," to the exclusion of the humans in the family. They were warned that the bond Puppy #1's made with them would be broken by introducing a second pup.

Never have heard this theory before, and would like another opinion.  

Thanks so much ~

Answer
I can see where the counselor is coming from.  Back when the dog guide school I raise puppies for, had fewer volunteers, they would occasionally place a second puppy in the same home, but wanted them to be at least 6 months apart.  On the other hand, I know many people get litter mates and do fine with them together. It might be just as well to wait a few months.  Note, I get a puppy every fall, sometime late fall, and winter housebreaking can be a pain.  Winter can also interfere with proper socialization.

Note, I forgot to thank you for rescuing the one puppy and planing a second.  I am very upset about all the dogs destroyed for lack of homes.  I do all I know how to encourage adoption and help those that do.