Intention

Imaams intention when women are included in the jamaat

Q: We are Hanafi. If I am leading the salaah at home, and my wife wants to read salaah behind me. What intention should I make? E.g. during ramadhaan, I read Esha, Taraweeh and Witr. Do I need to make an intention for each two rakaats that she is behind, or can I make an intention once for Esha and let it count for all. How must the intention be made? Verbally, in the mind, or just a realisation that she is behind me?