1.5 for me doesnt count. And in any event they gave T and P an entire family, yet wouldnt consider adding Kopa tio the canon? Vitani at the end of 2 has no one to be with, literally. at the end of 2 there are 2 guys in the pride, Simba and Kovu, and Vitani couldnt have cubs with either of them. Simbas too old and well Kovus her adopted brother. so, another Lk film, would in all likelihood have to deal with the other half of the family, the siblings of Kovu and Kiara. Now what would that result in? well in real lion prides if there is more than 1 dominant male, the males share ruling the pride. Kopa, since hes simbas son, would become king, and share with Kovu the responsibilities of ruling the pride. Kiara, since shes a girl, would not be affected by Kopa's return. Lion Prides have two hierachies, the male hierarchy, led by the king , followed by his soins, and then theres the female hierachy led by the queen followed by her daughters. so Kopa and Kiara would be coheirs and would have to compromise on who gets what. both would require consorts, so kovu is kiaras and vitani would become kopas.
