New "Buffy the Vampire Slayer" YA books will focus on Willow's kid being Chosen

So, how does this explain Willow having a child when she’s clearly been in a lesbian relationship with Tara in the original series, something that has always struck me as an immensely powerful and positive development in television programming. Perhaps Oz or Xander came forward as a donor?
With the Mouse Factory as owner, I don’t hold out much hope for a clear explanation.