I think that we all have mixed opinions on Scootaloo's parents, some like them and some don't, personally i really don't like them qvq, neither in personality or design (i like Snap Shutter but i don't like "mane allgood" design at at all qvq),i even felt like the episode was like "yay we are scootaloo's parents! ok lol bye forever!" so here are my headcanons! Remember these are not canon in any way and are just my interpretation~
1) Snap Shutter and Holiday always liked to travel, Snap travelling to find rare creatures and plants, and Holiday travelling to exotic places. Since they were foals Holiday was very protective of his little brother, if Snap messed something, she would fix it, but Snap got very used to this.
Cockatoo Sing-along (my version of Mane Allgood, i know her name is a play of Jane Goddall, but…it really doesn't fit her in m y opinion other than for "haha horse pun funny"), was the younger sister of Artifact Keeper (A.K Yearling a.k.a Daring Do) and Park Ranger (Flash Sentry's mom in my hc). Their parents being an archeologist and a journalist/linguist, they always were in touch with nature, so it wasn't a surprise when Cockatoo started studying to be a biologist.
2) Snap Shutter and Cockatoo Sing-Along relationship was love at first sight, and married in an express-wedding kind of way. They really didn't wanted any children, but many years later they found out that Cockatoo was pregnant. They didn't really took too many precautions during her pregnancy (this is why Scoot's wings are undeveloped) and when Scootaloo was born, they didn't knew what to do.
3) It was very unexpected to Snap to even visit Holiday in her house, and it was even more unexpected when they showed up carrying a baby in their arms ( a very sick looking baby). They asked her to watch over her, that it would only be for a little while and then they would come by and pick her up, Holiday was shocked with how the baby looked, sick and malnourished, and for the first time snapped at her brother, she told them her and her wife Lofty would take care of the baby, but to not come back until they learned how to be responsible parents.
Lofty and her absolutely adored her niece, and their twins Shimmy Shake and Lighthoof loved her as well. Lotfy couldn't fly because of an injury, so she related to little Scoot in their inability to fly.
Snap and Cockatoo visited her ONCE (they sent her happy birthday cards with photos but that was all) and it was the time they wanted her to move with them to Shire Lanka.