Nope I don't have the link sorry I'm only reading spoilers through the comments and novelupdate forum. And well I guess at that time baby weren't at the top of their priorities. And to answer ur question, it's pretty simple, she wants power, by having a baby with Wolfgang both of them gain more political power, so it's a win win I guess.
I think it is all speculation, nothing is set on stone yet, it does seem like red hair and wolfgang would make a good king and queen and they both would have their own business needs met with the heir and her becoming queen and what not... But I still believe there will be a magical bastard son out of nowhere who can free Wolfgang and Shin of this issue, the loophole can easily be covered in this story with a random extra character from the female bastard knights, I'm telling y'all lol I'm sticking to my theory (≧∀≦)
Its not that big of a deal banging someone else for one night, 5 minutes, to solve all your problems. People over value sex and we all know there would not be an ounce of emotion between them, it would all be for the sake of a transaction and tradition. This is why concubines have always existed ヾ(❀╹◡╹)ノ~
ANYWAYS, i hardly doubt this is happening, i don't ever see the king doing the deed with anyone else other than Shin. I still stand with my initial theory of somehow one of the batard female knights being eligible to bare a child or something and everyone is happy.