templated Attorney-Client Idiom lack of enhancement

I was trying to apply the Attorney-Client Idiom (know as PassKey Idiom) and this for two classes.

I explain :

I have a class named Secret which contains name and age as private members. I have created a class Attorney which defines 2 getters for each memeber in class Secret.

I want to create 2 classes:

1. showAge which only have access to 1 getter
2. showAgeAndName which has access to both getters.

So far all works fine, but looking at the code, it not well maintainable : if I add new members to my Secret and want a specific access to new getters I have to add another class and end with lot of copy-paste.

So is there a better alternative like : using Factory design pattern / enhance the templated class ...

Below is my code:

using namespace std;

class Secret;
class showAge;
class showAgeAndName;

template<typename T>
class Attorney
{
private:
    friend T;
    Attorney(const Attorney&) {}
    Attorney() {}   
};

class Secret
{
public:
    std::string getAge(Attorney<showAge>) noexcept { return "Age is " + to_string((long long)age); }
    std::string getName(Attorney<showAgeAndName>) noexcept { return "Name is " + name; }
private:
    int age{36};
    std::string name{"Mike"};
};

class showAge
{
public:
    showAge() noexcept {};

    void showInfos(Secret& src)
    {
        std::cout << src.getAge(Attorney<showAge>()) << std::endl;
    }
};

class showAgeAndName
{
public:
    showAgeAndName() noexcept {};

    void showInfos(Secret& src)
    {
        std::cout << src.getName(Attorney<showAgeAndName>()) << std::endl;
    }
};

int main() {
    Secret s;
    showAge prA;    
    showAgeAndName prAn;
    prA.showInfos(s);
    prAn.showInfos(s);
}

Thank you