On the return journey, the Knight of Marshall and Abel went to Matthew's Castle first. For the sake of clarity, the territory around Marshall Castle was already under Abel's possession.
As the entire Mathew family was no longer, the area that was 100 miles in between the Bennett Knight's domain and Harry Knight's domain was technically unclaimed. The same could be said for everything that was in Harry Castle.
While Abel didn't ask for it, he was granted the authority over these said properties. He could design his new Coat of Arms now if he wanted to, but he would have to wait for it to be approved after going to the ceremony in Bakong City.