introducing 2 male babies

Question
Hi,
    We have had 2 male guinea pigs for 1 1/2 years, they were brought home from Petsmart as babies, most likely from the same litter, and got along beautifully.  Spike was the dominant, but both very sweet to each other.  Last week Cocoa started to starve, and the vet determined malocclusion.  He went downhill so quickly that I had to euthanize him.  Spike and I were very depressed, and the void in the cage was overwhelming.  I decided to get Spike some new companions before he became depressed to the point of not eating.  Brought home 2 new male babies, followed Caviespirit's advise on introductions, which was spot on.  They all just spent their first night together in the big cage, and seem to be more comfortable than the beginning, but how long should it take before all 3 start playing and acting happier?  Spike continues to rumble and mount the younger ones, which I fear is so stressful for the babies.  Any advise?  Thank you.

Answer
Congratulations on your new babies. I'm sorry you lost Cocoa.

Adult males will accept the young pigs easily. The mounting and rumblestrutting is normal and will stop in a few days. It's not going to stress the babies, they're pretty adaptable. Spike is responding to his hormones that say if there's another new pig in the cage it must be for breeding purposes. He will find out the truth and will give that up.  

Mounting is not always a sexual response, it's a dominance issues. All animals do this, even sows. It's always an issue when introducing new males to a cage, even babies.  As far a playing with one another they may not necessarily play with Spike, but you'll see the little guys popcorning around the cage just to show their glee. It means life is good and they're having fun.

Give them time and things will settle down. Typically it takes about a week for everyone to settle in to their new routine.