Asking this specifically because one of my merc bands merged with my levy force so I now have a growing 6k merc mob with 10.500 limit, and can declare war asagain as my Levy was disbanded after the fighting. Quite enjoyable.
But how can I do this manually and not by accident? I managed to attach units in the correct order, but still they move in different speed then etc. causing trouble (besides of the above mentioned glitch). Is there a specific command to merge forces to one unit as the AI automatically does whenever assembling armies?