If you want to simply execute both packages at the same time, you can simply create a third package where you drag and drop the "Execute Package" task twice.
If you want to actually import the details of the two packages into the same package, that's a bit harder. You can use the "save as" command from the package save both the packages as Visual Basic Modules, then use your expertise in VB
to manually combine them together.
Hope this helps you.