This is a quick sample I put together after a post in our newsgroups. I don't think we have this functionality but I could see that some users (especially those with thousands of items in their inventory) could use this. So this sample is to show how the classes in our SDK will allow you to have this functionality. I'm going to use the LoggingIn sample from our SBA SDK that takes care of initializing the ISmallBusinessInstance for me. I'm going to use SBA's sampleproductcompany (Northwind Traders) and for this sample, I'm going to look for Kits that contain the "Snow Spors Helmet, Adult" item.

public void FindKitsThatContainMyItem()
{
    Debug.WriteLine("Finding Kits that contain 'Snow Sports Helmet, Adult'");
    // use DataView to find all Kit Items
    DataView itemsDataView = utilities.SbaInstance.ItemAccounts.DataView;
    itemsDataView.RowFilter = "AccountTypeID=" + (int)AccountType.KitItemAccount;

    foreach (DataRowView dataRowView in itemsDataView)
    {
        IKitItemAccount kit = utilities.SbaInstance.ItemAccounts.GetByDataRow(dataRowView.Row) as IKitItemAccount;

        foreach (IKitMember kitMember in kit.KitMembers.ChildList)
        {
            if ((kitMember.NonKitItemAccount != null) && (kitMember.NonKitItemAccount.Name == "Snow Sports Helmet, Adult"))
            {
                Debug.WriteLine(kit.Name);
                break;
            }
        }
    }

    Debug.WriteLine("-------");
}

I'm not using any UI in this sample, so the next step for anyone interested in this functionality will be to create a SBA UI Addin that exposes this functionality in the Item Form, shows a list of Kit Items and then allows you to open those forms. If anyone is interested in that, please let me know and I'll post some sample code for doing that.