Okay, so from all my years of research, google searches, and going through the backwaters of behind-the-scenes clips, promotional commercials and even the tiniest mentions in the series, sing-a-longs and various pre-2000 websites (ya' know, when fanart sites and art sites were using webrings?), I found 12 out of Pongo and Perdita's official 15 puppies.
The other three are never named. And, no, I don't believe that wiki answer that the three missing names are "Thunder, Purdy and Spotty/Dotty."
Of course you can come to your own conclusion, I just don't think those names are official.
SO, because I didn't want to leave the set short of three pups, I took 3 and gave them names--these are the three pups that were sitting in the chair during the "ThunderBolt show" scene in the 1961 movie: www.disneylove.com/wp-content/…
I'm don't think that middle pup was supposed to be Two-Tone, but you never know, it's not the first time a movie has changed its characters' appearance from promotional/poster images to the actual movie (when the sequel made Lucky's ears white I almost had a heartattack).
From left to right, meet "Spots"--a male, named for his many chest spots, since very few of the Disney dalmatians have spots on their chest/underbelly
"Dabble"--a male named for his single "dabbled" black ear
& lastly, "Pawprint"--a female named for her kinda pawprint-shaped spots on her ears and body.
I've nicknamed the "Chair Pups" or the "Shhh Pups," since they're the ones that tried to keep everyone quiet while watching TV. Just because I like them together, I'm going to assume they grew close to one another, forming their own trio, kinda like Lucky, Cadpig and Rolly.
"Spots," "Dabble," "Pawprint" & "101 Dalmatians" (c) Disney Inc.