A new feature in Microsoft Dynamics CRM 2011 is the ability to create Custom Activity entities. You can create a custom activity entity by checking the Define as an activity entity field.
While working with a Custom Activity entity you may notice some fields of type Party List such as Customers, Partners, and Organizer (for more information please visit Party List Types).
When added to the form you may notice that these fields look like Lookup fields but may function a little different. For example the Partners or Customer party list fields let you select multiple records of the same or different type.
You may also notice there aren’t any 1:N relationships defined for these Party List fields. This is because these fields point to the Activity Party table. Anytime a record is added to the Party List fields an associated record is created in the Activity Party table.
You can use the Activity Party table to get a complete view of all the Part List participants.
To retrieve Custom Activity records for only a certain participant in a Party List you can use Advance Find. For example, the use of Advance Find will search for all records that have John Doe in the Customer Party List. From the Custom Activity select Activity Parties form the related list.
Then select Party (Contact) from the related list. Select the Full Name field and enter the name of the Contact then click the Results button.
That’s all there is to it. No need to be a CRM Expert.