I can see why someone would think there was Terrier, but I'm not so sure about Basenji. (The only way to know for sure is to do a DNA test.) Both of your dogs look very similar. What breed, or mix, is the older one?
Such pretty pups! Nothing like a tri-baby (times 6!).
I'm sure their eager parents-in-waiting appreciate watching their pup grow… and of course, we're all enjoying it vicariously. :)
The traits you described are also found in most of the Nordic/spitz type dogs. I don't see anything overly basenji-ish about him in the pics. What ever he is, he's very hansome.