The two other adults of the wolf pack aren't all that interesting, but they fill key roles within the pack. Silver is the mother. She's Amaroq's mate, and raises all the pups. She's stern, but ultimately loving.
Nails is like a "spiritual father" (1.93) to the pups. He's not their real dad – that's Amaroq – but he's there for the pups when they need him, and he's there for Amaroq, too. He's clearly a loyal friend to Amaroq, which helps keep the pack together.
Goes to show you that each member of a wolf pack has a role to play. Sounds a little like a human family, don't you think?