How can I reset the index of child nodes in SAP CPI?

[DungVT37]

Hello everyone,

I have a first payload in XML format as below:

<SalesOrderList>
	<SalesOrder>
		<SalesOrderNumber>111</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0001</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0002</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
	</SalesOrder>
	<SalesOrder>
		<SalesOrderNumber>222</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0003</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0004</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0012</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
	</SalesOrder>
	<SalesOrder>
		<SalesOrderNumber>333</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0022</Line>
			<Material>ABC</Material>
			<Number></Number>
		</SalesOrderItems>
	</SalesOrder>
</SalesOrderList>

In SAP CPI - Message Mapping, I want to change to the new payload as below:

<SalesOrderList>
	<SalesOrder>
		<SalesOrderNumber>111</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0001</Line>
			<Material>ABC</Material>
			<Number>1</Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0002</Line>
			<Material>ABC</Material>
			<Number>2</Number>
		</SalesOrderItems>
	</SalesOrder>
	<SalesOrder>
		<SalesOrderNumber>222</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0003</Line>
			<Material>ABC</Material>
			<Number>1</Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0004</Line>
			<Material>ABC</Material>
			<Number>2</Number>
		</SalesOrderItems>
		<SalesOrderItems>
			<Line>0012</Line>
			<Material>ABC</Material>
			<Number>3</Number>
		</SalesOrderItems>
	</SalesOrder>
	<SalesOrder>
		<SalesOrderNumber>333</SalesOrderNumber>
		<SalesOrderItems>
			<Line>0022</Line>
			<Material>ABC</Material>
			<Number>1</Number>
		</SalesOrderItems>
	</SalesOrder>
</SalesOrderList>

As you can see, the <Number> increases for each <SalesOrderItem>, but after a new <SalesOrder>, the index is reset.

How do I get this in SAP CPI?

Thank you!

SAP Integration Suite