I think I don't fully understand your question. You can have this :
Foo1 -> Foo2 : msg 1
Foo1 -> Foo2 : msg 2
Foo1 -> Foo2 : msg 3
Foo1 -> Foo2 : msg 4
You can also choose to deactivate Foo1 before Foo2. But I guess this is not what you are talking about.