Hi
Ok what I do is pretty much the same a Luka author of the sako galib.
Make a small box tag it lever_water_rudder
with a preprocess for
var ID lever_water_rudder
operation FInRange
value1 0
value2 10
Now any part that is child of this will show when the water rudder is in the up possie
you can use any animation Im just using the water rudder as an example
Now if you link the canopy to the water ruder via a hidden xml gauge,so that when the canopy is at 90% open the water rudder drops the parts will disappear that are linked to it
Now this will off course happen on the ground as well so you need to add a ground test flag in either the xml gauge or as a preprocess in fsds as Felix has explaned over at FFDS forum.I normally build 2 vers of anything that is effected by the ejection sequence and tag orig on ground and the copy off ground,like canopys seats ect so when the canopy is opened on ground I can animate normally,in your case as it effect a majority of you aircraft to disappear I would use the rear canopy tag to model the ejection sequence make a little box call it r_canopy animate the box so it follows the path of the ejection
link the f_canopy to this and the seats pilots ect so when shft e 2 is pressed the ejection will happen when sfht e is used the canopy will open normally.Link the other parts to the water rudder and make the xml gauge drop the water rudder when r_canopy is opened then you will have a zero zero ejection seat

.Oh yeah in order to get the water rudder to work you need to add
point.# = 5, 0.0, 0.0, 0.0, 0, 0, 0.0, 0.0, 0.0, 0.0, 0.00, 3.00, 0.05, 0, 0.0, 0.0
to the contact points where point.# is the next number
in your contact point listing
hope this helps have a play see what happens and ask questions

(assign a water rudder key stroke in fs9 to test if the gauge is going to be a prob for the time being:) )
Wozza