Vanessa had a child during seasons 2 and 3 of Daredevil.
With the theories that Daniel was Fisk's son, I ended up with the character stuck in my head, and I thought, could Vanessa have already had a child with Wilson? And the time period that would work is when Fisk was arrested and Vanessa was sent abroad, she discovered she was pregnant, but preferred to hide the child so that he wouldn't risk his father's life, at least during his childhood.
From here on, there may be spoilers for episode 4 of season 2 of Born Again. What if, after the events of the last episode, at the end of the season Fisk discovers him, who would be around 11 years old, and brings him to train him to be his successor? Something that could refute this is Vanessa's statement in episode 3 suggesting that they should have a successor. Why would she say that if she already has a son? Perhaps she's actually trying to prepare Fisk to introduce their son, which she might think would be the ideal moment, since she was afraid of dying to Bullseye and believed it was better to introduce him to his father before that happened.
That's the theory, and what do I think? I think I'm wrong, hahaha. I thought about it, and if it's well-developed, it could be a good way to introduce Richard Fisk and show his training until he becomes Rose, but I don't think it will happen. And that statement from Vanessa that I mentioned makes it even more improbable, not to mention that it would be very difficult for her to have hidden this all this time. But it's something interesting to think about.