Windows XP SP3 32-bit
Attempting to edit existing Family instance variables by right-clicking on the Family, and trying to change values (not the name or type) just attempting to change initial values results in:
"Name used by object type in this family"
The object 'XXXX' in this family is using this name 'FireInterval_Min', so your variable needs a different name.
<img src="http://dl.dropbox.com/u/12667027/Construct%202/Family%20Instance%20Variables%20Bug.png" border="0" />
<img src="smileys/smiley19.gif" border="0" align="middle" />
EDIT: Forgot to mention, Archer_Ally is a sprite with no instance variables of its own.