So basically the datapack change the way you get the Aether Dragon in Dragon Mounts Legacy,
With this datapack you will only be able to convert the dragon egg into aether dragon egg by right clicking it inside the aether dimension or nearby aether blocks.
The datapack was scripted and tested using minecraft forge 1.20.1 alongside dragon mounts legacy and the aether mod. I recommenf setting /gamerule randomTickSpeed 100 because sometimes the egg conversion takes a long time.
NOTE: If the datapack doesn’t work, open your .minecraft/mods folder and find the Dragon Mounts mod file. Open both the mod file and the datapack using 7-Zip or WinRAR, then copy the datapack content into the mod file.