Create va_list dynamically

I have a function

void foo(int cnt, va_list ap);

I need to use it, but requirement is quite strict, number of va_list vary and it will change during run-time. What I would like to do is:

create a va_list (which expects char*) form

QList<Contact*>

where Contact is a defined class

class Contact
{
   public:
      QString getName();
   private: 
      QString m_name;

}; 

and I would like to populate in the loop va_list for example:

for (int idx = 0; idx<contacts.count(); idx++)
{
    contacts.at(idx)->getName(); // this i would like to pass to va_list

}

Does anybody have a clue about how I could do this?