I don't even know how to explain the existence of this herd in my head.
Children from left to right (from eldest to youngest): Petrel (Black Diamond Apple), Olive oil (Apple Cider Vinegar), Apple Turquoise, Apple barrier.
The Apple family has a tradition of giving names associated with apples. Therefore, even if you have a different name, you are given a second one. The tradition applies to both children and adults who have joined the Apple family.
It's a little awkward for me to tell their polyamory mess, but the sequence is something like this:
1) Everything is fine, everyone is going about their business, without relationships, all friends. Rarity has her own cool business, Applejack runs a farm.
I think in the past, Applejack could have had a short-term relationship with Rainbow Dash, but they ended because Applejack wanted a big family, and Rainbow was like childfree.
2) At one of the social events, Rarity meets Thunderlane. Due to close conversations and alcohol consumption, drunken sex with conception occurs. (Everything is voluntary, just two morons)
3) Thunderlane is not aware, and Rarity, when she finds out about the pregnancy, decides to keep it.
4) All her friends help her, including Applejack. Something is beginning to emerge.
5) Then Trenderhoof arrives, wanted to visit Applejack and Rarity as a friend. Learns about the situation, decides to help.
6) Chaos, everyone somehow got attached to each other, they have a polyamorous relationship, conceived a second one.
7) One day Thunderlane appears. He is shocked, as he was ready to raise a child, and Rarity did not inform him. Everyone is swearing, screaming, crying.
He ultimatum declares that he will help and he doesn't care whether they like it or not. Because it's his child, too.
8) As a result, he is very often on business trips (the problem of working at Wonderbolts), but he comes regularly. The rest of the guys in the herd warmed up to him. Then I even moved in with them and now they live as one big family, all the adults look after the children and it doesn't matter whose they are.