yes, sunzi... if a unit is support moving, it can be support held. Basically the unit isn't issuing a 'move' order.
Mud: A neat trick is to support your own unit into the unit where your unit is moving. For example, if I'm in gas, spa, and mars, and I want to move mars-bur but am afraid lyon will support pie-mars, I can do the following:
mars-bur
spa-mars
gas sup spa-mars
Now if pie-mars with support happens, it is 2 on 2 and they bounce, regardless of whether mars-bur succeeds. Make sense?
And, before anyone asks, no, you cannot displace your own unit with another one of your own units.