Yes, you can call one script from another.

To be certain that it will work as you expect, you need to be sure to qualify the path. The directory that the scripts are unloaded into is available in an environment variable %KIXCRYPTDIR%

To make your script portable you could do something like:
code:
If %KIXCRYPTDIR%
   $sScriptPath=%KIXCRYPTDIR%+"\"
Else
   $sScriptPath=".\"
EndIf
   
...later in your script...
   
Call $sScriptPath+"part2.kix"
Call $sScriptPath+"part3.kix"
The only script you won't be able to call is the "master" script, as although the file name is available in %KIXCRYPTFILE% the script is overwritten and deleted as soon as possible after the primary command begins to execute.