Need to add a Header in Message Mapping according to a field in under Item level

Hi All,

How can i get the output  using message mapping.

I have a structure similar to the one given below:

<Recordset>

   <Item1>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item1>

    <Item2>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item2>

    <Item3>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item3>

    <Item4>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item4>

    <Item5>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item5>

    <Item6>

     <Forcast1>

     <Forcast2>

     <Forcast3>

    <Item6>

</Recordset>

I need to add a HEADER before Item which have same  Forcast2 values using Message Mapping. For ex Forcast2 have these values(20,6,12,20,6) respectively. Then output should be:

<Recordset>

<Header1></Header1>{This Header will have value of Forcast2 which is same for Item2 and Item6 ie 6}

<Item2></Item2>

<Item6></Item6>

<Header2></Header2>{This Header will have value of Forcast2 which is same for Item3 ie 12}

<Item3></Item3>

<Header3></Header3>{This Header will have value of Forcast2 which is same for Item1 and Item4 ie 20}

<Item1></Item1>

<Item4></Item4>

<Recordset>