NSIS do things if section is not checked

I have created an NSIS Installer which works fine. Now I want to add another section called "install as update" which only will do things when it is NOT checked.

Why: When the full version is installed, it will overwrite certain files which contain the activation codes of the software.

I can do it otherwise, and make a section called "install full version", but that makes less sense.

Section /o "Install as update" SecUpdate  
    *if(checked == false){
        SetOutPath "$INSTDIR\data"
        File "data\ConfigFile.xml"
        File "..."
        File "..."
        File "..."
        File "..."
        File "..."
        File "..."
        File "..."
    *}
SectionEnd

*these two lines represent what I would like to do.

Solution

If a section is unchecked then the code in it will not execute no matter what you do so you have to put the code somewhere else. A hidden section is a good solution:

!include LogicLib.nsh
!include Sections.nsh

Page Components
Page InstFiles

Section "Program files"
SectionIn RO
;SetOutPath ...
;File ...
SectionEnd

Section /o "Install as update" SID_UPDATE
SectionEnd

Section -OverwriteActivation SID_OWACTIVATION
SetOutPath "$INSTDIR\data"
File "whatever.xml"
SectionEnd

Function .onSelChange
${If} ${SectionIsSelected} ${SID_UPDATE}
    !insertmacro UnselectSection ${SID_OWACTIVATION}
${Else}
    !insertmacro SelectSection ${SID_OWACTIVATION}
${EndIf}
FunctionEnd