Collision bubble query

Can you edit the collision bubble on imported aircraft ? Mdledit only seems to work on the stock ones.
If you edit a stock plane's bubble, and then use it as the 'mother' for an FSDS aircraft, will the 'child' also have the modified bubble ?
If you edit a stock plane's bubble, and then use it as the 'mother' for an FSDS aircraft, will the 'child' also have the modified bubble ?