I don't think that Kopa was killed by Zira. it just doesn't make sense. first off, one TLK2 book informs us that the Outlanders were banished from the pride by Mufasa, not Simba, and quite possibly before Simba is even born (which would explain the lack of appearance in the movie). this goes along with the quote from Simba, "My father's law will prevail." now from that, we can gather that Zira wasn't banished for killing Kopa but for being a troublemaker before the cub was even born. second, at the end of the battle after all the Outlander lionesses have "seen the light," Simba offers to put the past behind them and accept Zira back into the pride. now if she was responsible for the death of your son, since plotted to kill you and your daughter if not the entire pride, and has shown no hesitation to kill her own cubs for not joining her, why on earth would you let her back into your pride?! I don't think even Simba is THAT forgiving, and certainly not that foolish. he wasn't going to let Scar stay and said he deserved to die, so why would he let Zira? which leads to the concept that she was banished for a misdemeanor like the rest of her pride (and Simba should've let them come back beforehand since I'm sure they'd been punished enough by that point), and isn't responsible for anyone's death.
I'm actually think about making a short fanfic on a Kopa theory I came up with that I don't think anyone else has thought of. I'm just not sure whether I'm going to stick with it for my other fanfic, in which I plan to give reasonable explanation for all the plotholes. but I'm going to save it as a surprise until I write it
as to Mheetu, in my fanworld, his father takes him to another pride for safety before he gets old enough to be exhiled like the other young males. after his stay there, he decides he doesn't wish to return and lives happily ever after with them lol.
