Maybe we'll find a way to flash ZTE sticks sometime in the future, but for now I don't know how. Giving it to your wife is a good solution meanwhile.

Before you buy a Huawei K3565 at Mediamarkt, have you checked if there's a The Phone House shop near you, where they sell one of the better sticks (K3520, E172, K3715) for € 30? Details at
Der UMTS-Stick und -Datenkarten Schnäppchen Thread - Telefon-Treff