Bi-directional hash map, with a vector as value

struct MyStruct
{
    vector<A> a_vect;
    vector<B> b_vect;
    std:string my_string;
}

I need to maintain a data structure that maps a key:

int key;

To an instance of MyStruct.

And also vis-versa, so if I receive: A a or B b or std::string c I can find back which key points to a MyStruct object that contains a vector that contains a or b, or the string c.

I was looking at boost::multi-index map but couldn't find if this is doable. If so, how?