Having now read Wolves of the Calla 4 times, I'm surprised King didn't write the ending a little differently. SPOILERS AHEAD:
King has a penchant for twist endings, and tormenting his characters. I'm surprised he didn't have all the children in Wolves killed in the end by Cantab of the Manni. At the very beginning, Henchick proposed simply killing all the twins so the wolves went back to Thunderclap empty handed. When the time for the battle came, Roland has Cantab escort the kids to their hiding place. It would have been a classic King move to have Cantab, unbeknownst to the ka-tet, kill all the children due to lack of faith in the gunslingers to get the job done.