okay great thank you for the info!!!!I've been through this several times. Don't be surprised if the older dog doesn't want to play very much. The pup will have a lot more energy than the older dog and might get told to "leave me alone". They do work it out. Just watch the pup trying to bite or play since the older dog might not like it. Play bows will be a good clue to the acceptance of the pup.
My 2 year old and the pup are inseparable, the 7 year old tolerates the pup. The last pup I had was with an 8 year old and they were the same way, no fights but not a lot of play. As others have said lots of room and leashes on all.
Two crates, one in each living area, make things easier.