It is common engraving practice for “two or more players – or a divided string section with only single notes per division” (Gould 2011) to share a staff in an orchestral score, such as clarinet I and clarinet II. This practice addresses issues such as stemming, sharing musical content, placement of ties and slurs, and more. With respect to these engraving conventions, a comprehensive music encoding should also capture the semantic independence of the parts, which is essential for parts extraction or performing automated analysis. Currently, there are no exhaustive encoding guidelines that adequately address this topic. MEI provides a few examples and general recommendations, but there is no dedicated section such as Stave sharing (cp. Gould 2011). Additionally, there are no encoding guidelines from other projects or relevant publications. Only a few related MEI encodings are available in open access, but they tend to have a bias towards the visual domain. The proposed encoding guidelines were developed in the context of the Digital Interactive Mozart Edition for the encoding of the symphonic repertoire. The guidelines establish general rules and offer case-based solutions, as well extending MEI. As a proof-of-concept, a basic parts extraction tool has been developed with the potential to evolve into a full-fledged MEI parts creation tool. Extract Parts has been published on GitHub (https://github.com/ism-dme/DIME-tools) and is available for use by any project, provided that the MEI data adheres to the encoding guidelines proposed in this paper.