Curate, connect, and discover
People are right to say that you can’t really criticize Discovery for making it so that Spock grew up with a sister that no one knew about when TFF also gave him a secret sibling but I also want to add that Spock isn’t the only Star Trek character that this has been done with. Worf, Deanna Troi, and Tasha Yar were also revealed to have siblings that no one knew about or who were previously never mentioned (and, like Spock, Worf has 2 siblings, one by birth and one by adoption.)