Мне очень непонятно, какова ваша настоящая цель, но проверить состояния раздела можно следующим образом:
!include LogicLib.nsh
page components
page instfiles
SectionGroup /e "Group 1"
Section "G1S1" SEC_G1S1
SectionEnd
Section /o "G1S2" SEC_G1S2
SectionEnd
SectionGroupEnd
SectionGroup /e "Group 2"
Section /o "G2S1" SEC_G2S1
SectionEnd
Section "G2S2" SEC_G2S2
SectionEnd
SectionGroupEnd
Section -Hidden
${If} ${SectionIsSelected} ${SEC_G1S1}
MessageBox mb_ok "G1S1 is selected"
${EndIf}
${If} ${SectionIsSelected} ${SEC_G1S2}
MessageBox mb_ok "G1S2 is selected"
${EndIf}
# Check the other sections here ...
SectionEnd