adoption with older dog already in the home

We have two yellow Labs. One is 16 1/2 years old,the other is 14. They are wonderful dogs, we have a friend with a Springer that is about the same size and temperament as our dogs. She is about 10 years old. The Springer needs a new home, but we are afraid our dogs will think we are trying to replace them. We would never do anything to upset them, what do you think? The older of our two dogs has cancer, but it is slow growing, and we had her spleen removed two years ago. Except for her age,that limits her, she is quite happy. We wondered what a expert,would advise us to do. Adopt or not?

Take the dogs to a public dog park to meet - it's neutral territory. See if they get along. Labs usually love a crowd, so there's probably not going to be much of a problem on their part.
   
Then bring the Springer for visits at your house. Do this several times.
   
Then have the Springer sleep overnight. Do this several times.
   
Then have the Springer stay over a few days.
   
Make sure the Springer has his own bed & dishes & toys.
   
If all goes well, you should be able to bring the Springer home.