maybe angry birds stella is a prequel to angry birds! I got to thinking this: after the death of gale (need to confirm but it could be true but if you think it is false then do not be interested in this theory) spoiler alert! See the last episode of stella before reading this, the birds and the pigs knew that the golden island was now dangerous because opening the volcano previously infected it with ashes and smoke so they moved to another nearby island.
The handsome pig was the most affected after the death of Gale and he becomes very stubborn to avenge her, so he names himself king and the birds tired of the stubbornness of the pigs so they move to the other side of the island where After a few days they begin to fall ill and Dahlia is also infected (she was the only one to stay on the island) with the ashes of the volcano. so that in order to conserve the species all the birds decide to reproduce but the ash was also genetically infected except for stella. later the flock of stella (including her) dies and red, chuck, bomb, matilda, hal and terence are born, they discover 8 eggs in a nest and of these they drop 2 in poor condition in the forest (pink and orange colors which explains why stella and bubbles make their first appearance in angry birds seasons). 3 years later 3 eggs hatch (jay, jake and jim) leaving 3 unhatched eggs which cannot do so because the birds in here actually died. The handsome pig (now known as King Pig) has become very fat and greedy in recent years and now that he knows there are eggs he decides to get them to have a memory of Gale and also have his best feast with them. The birds soon discover the plans of the pigs and develop a hatred towards them and become very overprotective with this trying to save what they believe to be new species. later the blues meet a newborn orange bird named bubbles in the forest but what happened to stella? well, when bubbles was born he snorted and accidentally kicked stella's egg down the hill where there was a swampy puddle where a pink bird named after his mother is born, in this place stella discovers bubbles and then becomes obsessed with these funny round wonders just like than her mother until she had lost them but her daughter found them again in another place and of another variety. later discovers the birds and becomes an addition to the flock
If you have any suggestions, questions or something you would like to add to this theory, leave it in the comments.