Aussie/B-Collie Mix and a New Aussie Pup

Question
QUESTION: I have an Aussie/BorderCollie mix approx 5-6 yrs we adopted 3 1/2 yrs ago..He's been an amazing dog at home, perfect with mine and all kids and we've never had an issue with him.  Recently I introduced my dog to a friends 18month old Great Dane, although very large he thinks he's the size of a Yorkie and is extrtemely ridiculously submissive. After a few visits in my home and thiers my dog is still a bit agressive with nipping and jumping at the Dane. it's a little un-nerving and I would say it didn't go well. I'm hoping he is just intimidated by his size..very tall and a 125lbs.  He's very playful and comfortable with multiple dogs in the neighborhood. Now we are bringing a 4mo.old Aussie pup home in a few weeks. I'm nervous about introducing the new pup. Especially since we will be gone a full day (My dog is staying at home with a sitter) and overnight to pick him up.  How can I make showing up with a new pup go smooth?  We've fostered a puppy at home with him for a very short time in the past and it went well..  He will assumingly be the alpha dog.. after me...with this puppy but I don't want to freak him out. I will introduce them outside the house,letting them sniff each other.. but after that..Any suggestions?   Thanks

ANSWER: My Aussie nips and herds Great Danes, too, LOL.  They must look like cattle to her;-))
Seriously, sometimes it is the fact that the dogs are so large, and sometimes it's just that some herders aren't friends with every dog they meet.  If you introduced the Dane to your dog at your home, he is probably considered an "intruder", to be herded out, or away from you.  

If a puppy is under 5 months of age, they are usually tolerated well by older dogs.  However, you do NOT want to just bring the dog into your house or have them meet in YOUR yard.  Some Aussies are quite territorial.  All dogs in this situation should meet on NEUTRAL ground, perhaps at a neighbor's home, or the local fenced in tennis court.  
Your dog will not necessarily be the "alpha" - and I hate that terminology, since dogs don't live in rigid packs like wolves - their social structure is a bit more fluid.  The dog that is bossy about going out the door first may be quite content to let his packmate have the wubba toy whenever he wants it.

You have the best chance for acceptance when adding a second dog of an opposite gender, but it sometimes matters more with females than males.
A reasonable spread in age is good, too.  HTH

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QUESTION: Thanks Anne.. one more thing... after they meet, sniff, run,and get the intial intro out of thier systems.. when we do eventually get them both home.. is there anything special I should do to make both of them comfortable?  I will keep seperate eating spaces, beds, bowls etc..should I pay special attention to either of them or make everythng equal as much as I can?  My 2 daughters will most likely pay a bit more attention to the pup although I have talked to them about ignoring our current dog and luvin him up! I want no jealousy between animals.. by the way both dogs are male.. 6 yrs and 4 months. God I hope this goes well!   Thanks again!

Answer
One of the best things you can do is to be a benevolent leader to both dogs - sometimes it helps, while you take the puppy to puppy kindergarten, to also take your older dog back to a refresher class to remind him that you are in charge of the home, so he doesn't feel he has to act on his own.  I don't advise that you interfere in doggie spats, though (and sometimes there won't even be any), so long as no dog draws blood on the other, or obsessively hounds the other dog or bullies it.  One of the best ways to see if one dog is too rough with the other dog (be prepared - some dogs really like rough play) is to gently pull the "aggressor" away.  If the other dog really was intimidated, he will usually leave, hide, or turn away.  If he was enjoying the play, he will try to re-engage.  Let them decide which of them will be "top dog" among the dogs, but you be "top dog" in the household;-))  
I think that you are better off with the Aussie pup than some others, since herders are often intimidated by the more physical play styles of Boxers, Labs, Danes and the like.  They prefer a lighter, more athletic, but less body-slamming kind of play, IME.  Let me know how it works out:-))