First of all, congratulations! I stressed and stressed for about a year about getting a second Yorkie, but I've never regretted it. I would have no qualms about getting a third and plan to in a couple years. That's the only advice I can give you that I'm confident about, though.
I got a second male, and it's been a problem. My first Yorkie, 2-year-old, 8-pound Eddie, won't allow 10-year-old, 4-pound Jack to play with any toys. Eddie is docile and friendly in all other instances, and they even eat out of the same bowl, but he insists on being alpha with Jack over toys. And his admonitions are violent. It's gotten better in the 6 months we've had Jack, but not good enough. Eddie plays nicely with a female chihuahua that visits regularly. Both are neutered. Based on my limited experience, I'd think twice before getting two males again.
As for walks, I always walk the two of them together, but we don't have a problem with big dogs picking on them. When one comes around, I've always had time to scoop one or both up if I sense danger. If big dogs attacking is a regular occurrence, then no, I wouldn't walk the two of them at the same time. It's a little difficult to get control of two dogs in a hurry.
Good luck!
__________________ Mike ~ Doting Dad to Jillie, Harper, Molly, Cooper, Eddie (RIP), Lucy (RIP), Rusty (RIP) and Jack (RIP). Check us out on YouTube |