I read this book 2 years ago, so I am a bit rusty on what happened. I hope this can help.
It is important for Winnie to consider the Tucks her friends, alone because the Tucks barely talked to other people. Winnie met the Tucks by chance and she talked to them. The Tucks barely had any other friends because they lived forever.
I kinda forgot a bunch of things, but I hope this can be a good starter.