Yes, please post the last round here, or at least the most current changes.
If that is the way that you have the line of succession set up, then yes he should most likely marry the older sister - unless she is already married! A marriage to an older sister may make it difficult in future Writing Prompts though. If you want to change and have him marry somebody else, then you could maybe have the sister abdicate in favor of the current king?
As for the next round, I was thinking about trying to get it up Sunday... but I'm being very slow on the rounds so that I don't end up overdoing myself... feel free to do the same :)