Sorry about the delay, to compensate it I will be posting twice this week.

1.Create a new Temporary Table with the following properties

Propertie Value
Name TmpBOMExplode
TableType InMemory
Field Extended Data Type
BOMQty BOMQty
ItemId ItemId
ItemName ItemName
Level Int
RefItemID ItemId

It should look like this:

TmpBOMExplode

2.Create a new Class, I will call it BOMDesign, and Modify classDeclaration.

class BOMDesign
{
    TmpBOMExplode tmpBOM;
}

3.Create a method to create the parent Item.

private int InsertParentItem(ItemId _itemId, int _level)
{
    InventTable inventTable;
    ;

    //Gets the parent information and then insert on TmpBOMExplode Table with level 0.
    select firstOnly inventTable where inventTable.ItemId == _itemId;

    tmpBOM.ItemId = _itemId;
    tmpBOM.ItemName = inventTable.itemName();
    tmpBOM.Level = _level;
    tmpBOM.BOMQty = 1 ;
    tmpBOM.insert();

    return _level+ 1 ;
}

4.Create a method that verifies if the current Item is also a BOM Item.

boolean hasChild(ItemId _itemId)
{
    BOMVersion  bomVersion;
    ;

    //Check if the item is also a BOM item.
    select firstonly bomVersion
            where bomVersion.ItemId == _itemid
            && bomVersion.Active
            && bomVersion.FromDate <= systemdateget ()
            && (!bomVersion.ToDate || bomVersion.ToDate >= systemdateget ());

    if (bomVersion.RecId)
        return true ;

    return false ;
}

5.Now, create the method which will explode the Item recursively, every time it calls itself we have to increase the level number.
The Level number is useful if you want to create a Tree Control later.

void itemExplode(ItemId _ItemId, int _level = 0, BOMQty _bomQty = 1)
{
    BOM         bomTable;
    InventTable inventTable;
    BOMVersion  bomVersion;
    ;

    //Insert parent Item
    if (_level == 0)
        _level = this.InsertParentItem(_ItemId, _level);

    //Verifies if the Item exists in BOMVersion Table.
    //The item must be active and not expired.
    select firstonly bomVersion
            where bomVersion.ItemId == _itemid
            && bomVersion.Active
            && bomVersion.FromDate <= systemdateget()
            && (!bomVersion.ToDate || bomVersion.ToDate >= systemdateget());

    if (bomVersion.RecId)
    {
        //Every item on BOMVersion has a BOMId which is used to show
        //which products belong to a BOM Item.
        While select bomTable
            where bomTable.BOMId == bomVersion.BOMId
            join inventTable
            where bomTable.ItemId == inventTable.ItemId
        {
            //Insert the items that compose the BOM Item with level 1.
            tmpBOM.ItemId = bomTable.ItemId;
            tmpBOM.ItemName = inventTable.itemName();
            tmpBOM.RefItemId = bomVersion.ItemId;
            tmpBOM.BOMQty = bomTable.BOMQty / bomTable.BOMQtySerie * _bomQty;
            tmpBOM.Level = _level;
            tmpBOM.insert();

            //This method is used to check if the BOM Item is composed by
            //another BOM Item, case true it will call the method recursively
            // with level 2.
            if (this.hasChild(bomTable.ItemId))
                this.itemExplode(bomTable.ItemId, _level+ 1, tmpBOM.BOMQty);
        }
    }
}

5.Main method used to test Class.

public static void main(Args args)
{
    BOMDesign bomDesign = new BOMDesign();
    ;

    bomDesign.itemExplode( 'D0001', 0 );
}

6.I have temporarily changed the TableType to regular so I can see the results.

TmpBOMExplodeTable