I do agree that I may be exploiting a loophole but there's also no guarantee I can effectively win that siege... My army is undermanned and a siege situation makes me lose any advantage I might have in using my cavalry...

As to the siege proper, Milan is a great city and it doesn't seem too farfetched to imagine one could squeeze a small force (under the same colours and talking the same language) past the besiegers and take the prize under their nose...

Plus, it makes for an interesting IC situation, I think...

But I'm willing to wait on Cecil's ruling, either way