How do I get a second mate for my other grown wolf?

Well you can’t. But if you want to start over a family with that wolf, go to the menu/front page. Click your animal, in the top left corner a family button is there. Click it, and then click the character you want to start a new family with, and if it asks if you want to do that, then click yes, or sure. But that character has to be at least lvl 10. But with the new update I think it has to be lvl 50.