This is how they need to do it:
Just like how the first BP had an opening that used a vibranium CG series of figures to give a summary of Wakanda's history, that same sequence can explain what happened since the first film.
T'challa got married, he had a child, but then he died from an illness. Now someone has to be the new black panther. T'challas child is too young so it falls on shuri to do it. Shes the one narrating the story to T'challa II. Shes also the one teaching him about wakandas history and technology.
By the second film he will be a teenager and by the third film a young adult. By the time he's an adult, he'll have inherited the genius of shuri, the power of t'challa, and the heart of Nakia. He will then be more in line with the character from the comics.
I'll take my money in cash Disney.