The King of the Sinyalian Kingdom soon found out about this alliance between the Noble Families. He was slightly worried as this alliance wasn't weak.
It could be considered a hidden danger for him. But dealing with them also wasn't a good idea. It would just confirm the suspicious held by these Noble Families.
First, he decided to spread some false rumors about the Walsh Dukedom. How Siluca was colluding with the enemy kingdom and so on.
Once those rumors had spread in the entire Kingdom, the King was going to check the reactions of these Noble Families. After that, he was going to take subtle action against one of them.
While taking action against one of the Noble Families, he was going to frame another one.
In this way, the unity between the Noble Houses would be shattered. Once this alliance is shaken, the King could easily deal with them.