siege engine questions..

Hey folks,
Im stuck at work and won't be home in several days, and I came up with some questions I'd love to have answered now...

If you have an army of greater than 16 units, and choose to start the battle with siege units... can you withdraw or rout the siege engine operators and bring in reinforcement units? Or does the actual engine have to be wrecked?

Also, during sieges.. is it possible to drag more than one army on a castle to commence a siege or are you limited to only 16 units? Seems to me a citadel filled with troops, catapult towers and walls would require many siege engines, but if you can't cycle out their crews for additional troops, or if you're limited to only the foot troops you can bring alongside the engines.. the battle sure wont be easy...

thanks in advance!

As soon as the crew is off the field, you can get another unit in.

You can set up with 16 Engines, tear up the castle, and get the infantry in exchange to mop up the place. (That is if the defender is not attacking your siege engines standing alone, never tried an all siege setup)

Thanks, Dragon. It had never before occurred to me to drag two armies one after another onto a castle, and have them both assault the place, I though one replaced the other.