It should be part of product only. because there is not replacement concept if there is no product sold.Replacement is part and parcel of product and may not exist on its own.May the term is misleading but we can read it as product replacement
Well not to mention again... without JAVA there is no Pega. And Java does support multiple inheritance in some way. Only to avoid Memory manipulations by developers and ambiguity of multiple inheritance JAVA is built that way.
Reportedly, Java inventor James Gosling has spoken against implementation inheritance, stating that he would not include it if he were to redesign Java. Language designs that decouple inheritance from subtyping (interface inheritance) appeared as early as 1990; a modern example of this is the Go programming language
Implementation inheritance is what seems to trip everyone up when it comes to pattern inheritance. If the inherited implementation applies use it, if not ignore it.
As stated earlier, data model inheritance is the primary benefit of using pattern inheritance.
With pattern inheritance the object class can change dramatically when traversing the class name right-to-left whereas with an is-a relationship the class in question is always a member of the class being extended.