[wix-users] Install an exe while my installer is running?

[Carlos Sosa]

Hello I'm working on an installer with a custom UI where the user can select which components to install.
The problem is that when the click install (SQL 2016 express) the SQL installer starts just fine, but since my Installer is running the SQL cannot continue.

I may be doing this the wrong way, any direction/help is appreciated.
I'm using a Custom UI, I noticed that after the custom UI closes wherever is in the main Product .wxs continues in my case if I understand correctly at least one component is needed, I'm using:

   <Component Id="CMP_InstallMeTXT"
                 Guid="E8A58B7B-F031-4548-9BDD-7A6796C8460D">
        <File Id="FILE_InstallMeTXT"
              Source="InstallMe.txt"
              KeyPath="yes" />
      </Component

So when the Custom UI is closed, the installation of this component continues.
How can I open a simple Window (custom UI) and only trigger an Installer (3rd party apps like .Net, SQL, etc) when one of the buttons on the custom UI is clicked? So the Main installer is not running while I try to install the other tools?

Thanks.