So this works wonderfully. This test snippet confirms that the for loop should look as I mentioned to cycle through the list of items matched by the FindItem. The below will simply cycle through everything in your backpack and display some detail about them. In your example you would simply replace my "Display" stuff in the below to "If Quest in #Property" yadda yadda.
finditem * C_ , #backpackid
for #findindex 1 #findcnt
{
event property #findid
Display OK Object Information:$
+ , #spc , #spc , #spc , FindCnt: #Findcnt $
+ , #spc , #spc , #spc , FindIndex: #Findindex $
+ , #spc , #spc , #spc , Item Type: #FindType $
+ , #spc , #spc , #spc , Item ID: #ltargetid $
+ , #spc , #spc , #spc , Color: #findcol $
+ , #spc , #spc , #spc , Properties: #property $
}
Halt