[PrincessDiana]

My advice is to let them meet on neutral grounds - somewhere the golden won't feel like the puppy is intruding. Keep them leashed and slowly introduce them. Maybe take them for a walk? After they are comfortable with each other, bring the puppy into the house.

Once in the house, it's important to make sure the "old" dog doesn't feel like it's being replaced by the "new" dog. They will need to work out their pack status on their own and it's likely the puppy will be submissive to the adult. Whatever they decide, you will be able to tell. Make sure you greet the old one first, feed him first, do everything with him first. Also - spend some one on one time with each dog to make sure they are getting individual attention. Take them for outings separately. It's important to make sure each dog develops it's own identity separate from it's pack. (I read a lot about this when we decided to get a second dog).

As far as the size issue.. I would let them play but only under very careful supervision. Definitely let them interact but when things get rowdy or you aren't there, keep them separate.

Hope this helps!