Word Add-in for Enhanced Collaboration

I need a Microsoft Word Add-in designed to enhance document collaboration. The add-in should facilitate real-time editing and allow users to assemble selected paragraphs or lines. Additionally, it should include customizable buttons for inserting predefined text blocks.

Key Requirements:
- Real-time editing capabilities
- Assembly of selected paragraphs/lines
- Customizable buttons for predefined text blocks

Ideal Skills & Experience:
- Proficiency in developing Microsoft Word Add-ins
- Experience with real-time document collaboration tools
- Familiarity with Word's API and custom button integration

Please provide examples of similar work done.