Allow / Disable speicifc copy ctor and assignment operations for templates

I am wondering if it possible to achieve something with templates. What I want to do is allow specific 'copy ctors and assigment operators' from one template to another and disable others.

I think I managed only one of the things that I want so I am providing the class below. For copy ctors or assignment operators I want to be able to do the below

• Foo<false> to Foo<false> always OK
• Foo<true> should only be allowed to copied or assigned to Foo<false>

I am not sure if it is possible...

#include <iostream>
#include <type_traits>
using namespace std;

template<bool Owner>
class Foo
{
    static constexpr bool owner_ = Owner;

public: 
    Foo() {std::cout << "ctor\n";}
    Foo operator=(const Foo& foo) { std::cout << "assignment\n";}
    Foo(const Foo& foo) { std::cout << "copy ctor \n"; }

    template <bool U>
    Foo( const Foo<U>& other)
    {
        std::cout << "copy ctor2 \n"; 
    }

    template <bool U>
    Foo<false>& operator=( const Foo<U>& other)
    {
        std::cout << "assignment 2 \n"; 
        return *this;
    }

    template < bool B_ = Owner, typename = std::enable_if_t <B_> >
    void bar1() {
        std:cout << "bar1 " << owner_ << "\n";
    }

    void bar2() {std:cout << "bar2 " << owner_ << "\n";}
};

At the moment the only thing that I have succeeded is that operator= will work for Foo<false> = Foo<true>. Foo<false> to Foo<false> is OK, but that allows all other conversions as well so Foo<true> to Foo<true> is possible.