I don't know if I was very clear in my first post...
Trying to describe the thing, it should come like this:
I have these 3 tables in a relational database: "Notifications", "Attachments" and the relational table that connects the two previous ones, named "NoticationAttachments". An "Attachment" is inserted first, within the application, and can be used in several "Notifications".
The main goal is to keep track of the attachments sent in each notification.
So, in a Silverlight application, when a new Notification is created, the user should be able to select some attachments that he wants to send among the notification. In order to facilitate my UI approach I've created a transient Property wich I've added (in the Attachment's Entity) to the ORM Entity generated code (as posted in this first thread intervention). That transient property is boolean and is called "Seleccionado" (wich means selected in portuguese) and I was using it in order to MVVM bind it to the Telerik's GridView checkbox column that points wich Attachment's are to be associated with the new notification.
The problem is that when the transient "Seleccionado" Property is changed, my Model Context detects changes on those attached selected entities and tries to submit changes among the new created notification... How can I avoid this?
I don't know if has any influence in the reported problem but the "Attachments" object has a byte property:
private byte _Conteudo;
[Column("CONTEUDO", OpenAccessType = OpenAccessType.Blob, IsNullable = true, SqlType = "BLOB")]
public virtual byte ConteudoProp
this._Conteudo = value;