Sweet, Wonderful Milo, I don't even know where to begin.
First I'd like to honor the lovely kitty Apple that was a VERY much loved cat and will be missed always. She sounds like an amazing cat who shares a lot of good memories with her family. A cat who you've known since they were first born holds a very special place in anyone's heart. Apple will always be loved unconditionally.

You had a hard job, Milo! But you filled the gap purrfectly "He was the missing part of the family puzzle."
Your family set out in hope of finding a new cat after Apple was gone. At first they thought it was pointless. With every family, there is one pet who is the one, and that was you! You were waiting there for them. With your gorgeous white and gold fur and those striking big blue eyes that would surly bring you lots of attention and catch the eyes of anyone! You are the perfect combination of playful, but also calm sometimes, and ready for a nap.

Apple will always be remembered and have a very important place in your family's hearts. Now you are a part of the family, and you fit right in. Although you were left at the shelter all alone after your sisters got adopted, (hopefully into amazing homes, too!) now you get to share the love every pet has and have an unbreakable bond with your humans. It was truly meant to be. Some would even say it was destiny that you found the most perfect family!

But all this love is just the beginning, Milo, you will get many more years with you family. Snuggling, playing, petting, rubbing, kissing, hugging, meowing, waiting eagerly for your food, traveling, loving. I'm sure you already have so many happy memories, but there are so many more still to come! You are a very special kitty, Milo. It really warms my heart to hear about a cat who has such a nice, welcoming home to live their in entire life in. Always feeling loved. Enjoy your day as the most deserving Cat of the day! EVERY day, in your family's eyes!