As many of you know, only one-to-many and many-to-one relationships can be created in Microsoft CRM 3. To create many-to-many relationships, the most commonly used technique is a “middle” entity, or mapping entity. However, there are several other options for the more pragmatic customizer. Please refer to the CRM-Team blog post:

http://blogs.msdn.com/crm/archive/2007/02/15/many-to-many-relationships-in-ms-dynamics-crm-3-0.aspx

Gustaf Westerlund
CRM and SharePoint Consultant

Humandata AB
www.humandata.se