How long does it take for pugs to bond?
So I have a dilemma. Backstory: I'm a new pug-mom, I've had one elderly pug for 2 years, and he's been the best, sweetest boy. He's 12 years old, and I adopted him from a pug rescue. It took about 2 weeks for him to acclimate to me since he is blind, but after those 2 weeks he has been an absolute joy and blessing. His name is Magoo, and he used to live with multiple pugs and he really enjoyed their company.
The problem: I decided to adopt a new pug, a 10 year old boy named Biff. His foster mother said he was very well-behaved and loved playing with the other pugs. I introduced him to my old pug by walking them both outside, and they seemed to get along fine. However, as 2 days passed the new pug has started to mark indoors and he's also started to hump and lick my old pug. I take them both out about 4 times daily, and I walk Biff for an extra 10 minutes each time since he was marking pretty much daily (it's been a week), and the marking hasn't stopped. He continues to hump Magoo, and now Magoo has been humping him back and they both take turns licking each other's penises. They don't bark at each other, or bite, I just don't know if it's good or normal. When they're not humping each other or licking each other, they just go their own separate ways.
Questions: Is it normal for boys to behave this way?
How long will it take a new dog to get used to his new house with an additional dog?
Will a belly band be a good solution to stop the marking?
Thanks so much!