The post came attached to a collage of pictures of Winter, 15, with sister Shanelle Workman-Gray, 35, and her family.
Winter began her post by wishing everyone a Merry Christmas and saying she was "so lucky to be a part of this amazing family."
"It's been about a year and a half and at the same time, been the best year and a half of my life, I love them more than I could ever describe and they've shown me more love than I ever thought was possible. They've each given me something incredible to carry with me for the rest of my life. They've taught me how to love unconditionally, how to give, how to forgive, how to find strength, how to comfort others, how to love myself, and how to be a young woman.
My sister is my best friend and one day I can only pray to have a family like the one she has created. I hope to be even half of the incredible person she is. She's done so many amazing things with her life and I will always look up to my big sister. I can't thank them enough and hopefully one day I can do something to show them how grateful I am. My nieces are the lights of my life, my sister is my better half, and my brother in law has been the best father figure you could ever ask for. He's the best dad and I couldn't be happier we all have him. Thank you for all you've done for me guys, and for always being there. I'll be here for anything, anytime, forever (we also live together...so just knock on my door anytime). I love you with all my heart. So here's to the rest of my life with my spectacular family! Merry Christmas everyone. Please be thankful for the amazing people and things you have in your life this year. I know I am."
Workman-Grey was appointed custody of the teenage Modern Family star amid allegations of abuse by their mother, Chrisoula Workman. While Workman has denied the allegations and has been looking to regain custody of her daughter, Workman-Grey herself was taken from their mother 20 years ago under similar abuse allegations.