Reading the Wix help I see that “Deferred execution custom actions must come after InstallInitialize and come before InstallFinalize in the action sequence.”

Well, I need to run an msi and exe in silent with elevated access after the completion of the current MSI installer.So what I’ve tried is on below,

During Silent Mode:

1. Added a Custom Action(SilentLaunchSecApp) with deferred execute
   before InstallFinalize

2. Action SilentLaunchSecApp will try to launch the process(another
   msi) in silent mode

Error : Another Installation is in progress. You must complete that installation before continuing this one.

To overcome this Error ,

1. Added the custom action with immediate execute after InstallFinalize
   and this is not allowing the process to run in elevated mode.

2. While executing in silent mode , the UAC prompt is not allowed to
   trigger hence its will try to run the process and exited with error
   says “Ensure that the process running the MSI installer has
   sufficient permissions”