How to group PortableApps Prgm and underlying Prgm Icon together in TaskBar?

Assume an users pins a shortcut to e.g. Firefox Portable to (Win7) TaskBar.
After clicking on it FirefoxPortable.exe setup environment and starts in turn the underlying core Firefox.exe

Since PortableFirefox.exe and Firefox.exe are strictly speaking two different programs another icon thunbnail appear in Taskbar.
So one PortableApp launch causes a second, different entry in TaskBar altough both belong somehow together.

Is there a way to group these two icons/thumbnails together just as if I would have started 2 instances of Firefox.exe?

Thank you
Peter