Scenario: Entity Framework 4 , POCO templates and Master Detail relation.

Lets say I have a master type like this:

//partial implementation of master entity
partial class Master
{
    public void AddDetail(x,y,z)
    {
        var detail = new Detail()
        {
           X = x,
           Y = y,
           Z = z,
        };

        //add the detail to the master
        this.Details.Add(detail);
    }
}

If I then add a master instance to my context and commit, the details will not be saved:

var masterObject = new Master();
masterObject.AddDetail(1,2,3);
myContext.MasterSet.AddObject(masterObject);

Is there any way to make the details to be persisted by reachabillity when using POCO templates? Or any other way? the Details collection in the Master entity is a FixUpCollection, so it ought to track the changes IMO.

So, any ideas how to make this work W/O killing the POCO'ness too much?