Star Trek: Discovery is supposed to be part of the main continuity, meaning that all this happens prior to the original Star Trek series that so many people love.
With five decades of history and committed fans, there’s a lot riding on the success of this show and these characters.
If it doesn’t work that well, it could turn off many passionate fans, which the series will likely need in order to survive.
If the creation of a new adoptive sister works as well as Sonequa Martin-Green claims, everything will be fine.