message bundling issue

Hi all,

I have a unbounded message with the following structure

messagename(unbounded)

Header

element1

LineItem

Item(unbounded)

orderno

lineitemno

ex:

message'1'

Header

a

Lineitem

item

1(ordnum)

10(lineitem)

message'2'

Header

a

Lineitem

item

2(ordnum)

10(lineitem)

message'3'

Header

a

Lineitem

item

1

20

Now , I want to group the message with the same order number.(messages 1 and 3)

The desired result woud be like,

message'result'.

Header

a

Lineitem

item

1

10

item

1

20

Can somebody help me in grouping this.

Thanks in advance,

sudha.