Ditto to what Jessi said. And, I don't know what the situation at the breeder's was like, but you can't assume that because the breeder had 30 basenjis, that this dog was socialized with other dogs. Some breeders have many, many dogs, but they all live in a kennel situation, and don't interact with other dogs. And being a show dog doesn't guarantee a dog that plays well with others either.
That being said, it isn't at all uncommon for basenjis to be friendly with the dogs in their family, or pack, and completely unwelcoming to other "stranger" dogs. It is way too early to determine whether your dogs are actually having problems, or just adjusting to a whole lot of changes.
I usually give a dog a few weeks, to a month of settling in before I introduce any new dogs or people.