When the interface of two representatives shows common features, we may deduce a polymorph structure of the programme from it. But how does systemic changeability happen and how plastic is the interface itself? The video deals with the intimate relationship between sisters on the basis of the mechanisms in the dynamic programming of objects. At a time when the concept of creative plasticity corresponds with the demands of capitalistic production, there is an effort to constantly redefine the common conditions of relationships. Within the framework of programming language, by every new redefinition we only eliminate everything that stands beyond the function. Therefore it seems risky to balance between plasticity and flexibility.