Multiple variadic parameters

I'm trying to do something like this:

template <class ... Required>
class Base
{
    template <class First, class ... Rest>
    void bar(First f, Rest ... r)
    {
        [...]
        return bar(r...);
    }
    void bar()
    {
        return;
    }
    public:
        template <class ... Optional>
        void foo(Required ... r, Optional ... o)
        {
            [...]
            bar(r...); //separate the required from the optional
            bar(o...);
        }
};

class Child : Base<Foo1, Foo2>
{
    public:
        Child()
        {
            [...]
            foo(foo1,foo2,foo3);
        }
}

But the first bar call is receiving all the parameters instead of only the Required ones, and the second call is receiving none of the parameters. Did I miss something about multiple variadic parameters? Shouldn't the compiler know that Required... is Foo1,Foo2 and the rest is Optional?