ideas for big puppies!!

So I've decided it's time to put down both of my labs. They're both 12 and have been together since they were puppies. Magnum can barley walk anymore and constantly falls.Moxie barely eats but seems so happy still. I know I have to put them both down together because if I just put magnum down moxie will for sure die of loneliness and a broken heart. All of this is so terrible to me... so I'm planning their special day and I'd love ideas of what to do for them!! They are outdoor doggies but recently I've decided to put them inside and I just have them a bath tonight. Any ideas will be appreciated!!