Conceptual modeling languages are of great importance within information systems management. During the last decade, a small set of commonly used enterprise modeling languages established and gained broad acceptance in both academia and practice (e.g., BPMN). Due to their dissemination, these languages often need to be extended or adapted for domain-specific or technical requirements. Since most modeling languages provide rather poor extension mechanisms, it is necessary to modify a language meta model directly. However, there is lack of integrated methodical support for these modifications. Within this position paper, we therefore proclaim a generic framework for modifying enterprise modeling languages on the meta model level. The framework is divided into the main parts of a modeling language (abstract syntax, concrete syntax, semantics) and respective operations (add, remove, specify and redefine).