Well, since I did Rainbow's Family (Link: https://derpibooru.org/images/3340409), I felt that I should do another family. So, here is the Belle Family (AKA Rarity's Family) for my headcanon!

Rarity (Marefriend and then later wife of Spike, daughter of Hondo Flanks and Cookie Crumbles, big sister of Sweetie Belle and niece of Fleur-De-Lis, FancyPants, Mary and Poppins)

Sweetie Belle (Daughter of Hondo Flanks and Cookies Crumbles, little sister of Rarity, sister-in-law to Spike and niece of Fleur-De-Lis, FancyPants, Mary and Poppins)

Hondo Flanks (Husband of Cookie Crumbles, father of Rarity and Sweetie Belle, father-in-law to Spike, brother of Fleur-De-Lis and brother-in-law to FancyPants, Mary and Poppins)

Cookie Crumbles (Wife of Hondo Flanks, mother of Rarity and Sweetie Belle, mother-in-law to Spike, sister of Mary and sister-in-law to Poppins, Fleur-De-Lis and FancyPants)

Fleur-De-Lis (Wife of FancyPants, sister of Hondo Flanks, sister-in-law to Cookie Crumbles, Mary and Poppins, aunt of Rarity and Sweetie Belle and aunt-in-law to Spike)

FancyPants (Husband of Fleur-De-Lis, brother-in-law to Hondo Flanks, Cookie Crumbles, Mary and Poppins, uncle of Rarity and Sweetie Belle and uncle-in-law to Spike)

Marry (Wife of Poppins, sister of Cookie Crumbles, sister-in-law to Hondo Flanks, Fleur-De-Lis and FancyPants, aunt of Rarity and Sweetie Belle and aunt-in-law to Spike)

Poppins (Wife of Mary, sister-in-law to Cookie Crumbles, Hondo Flanks, Fleur-De-Lis and FancyPants, aunt of Rarity and Sweetie Belle and aunt-in-law to Spike)

Spike (Dragonfriend and then later husband of Rarity, brother-in-law to Sweetie Belle, son-in-law to Hondo Flanks and Cookie Crumbles and nephew-in-law to Fleur-De-Lis, FancyPants, Mary and Poppins)

Headcanon:

The events of Season 8-9 (With the exception of The Washouts and Best Gift Ever) and Rainbow Roadtrip are not canon.

Instead of being manifestations of the Tree of Harmony, Mary (The pink pony with the yellow dress) and Poppins (The purple pony with the pink dress) are real.

Spike and Rarity start off as boyfriend and girfriend. However, after learning that he and all his friends can’t grow up due to a curse, Spike is devastated. While Applejack, Rarity and Rainbow comfort their little sisters, the dragon decides to cheat and turn into a adult by making a magic potion. At first, it seems like a good idea, until Spike learns something...he can’t turn back to a baby dragon! But fortunately, there is a silver lining as Rarity proposes to Spike and they soon become an official married couple. (Note:This is loosely based on this: https://derpibooru.org/images/3247414)