I've seen a lot of people on different communities try to connect both of Reki's worlds by claiming Kuroyukihime is Kirito and Asuna's real daughter, 20 or so years into the future...
However, in a couple recent interviews with Reki, he was asked if this was the case. He answered, with this.
There seems to be some conjecture that such a thing could be possible. However, it’s already said that Kuroyukihime’s family was not a happy one. If she was Asuna and Kirito’s daughter, in the twenty years between the time settings, they had a really bad falling out in their relationship. I hope she is not the daughter of Kirito and Asuna.
However, he also goes on to say this, in a completely different interview.
At this point the two shows are separate. As an author, I consider those two titles separate. There might be some various similarities between the shows. That’s not to say should some issues be resolved in both storylines, possibly, maybe, there’ll be a third series that ties to both titles? But I can’t say at this point.