How to add content after or before block using XML in magento

Question

I what to append content in block using XML file. Please check below image

I have added below code but it is overtiring content. (I want to appending).

<reference name="order_items">
      <action method="addColumnRender">
         <column>name</column>
         <block>adminhtml/sales_items_column_name</block>
         <template>sales/items/column/name.phtml</template>
      </action> 
</reference> 

I have checked core file there are creating block programmatically.

Answer 1

If you know the block names/aliases of both blocks you can move the block that is appearing first to display AFTER the block you want to appear first.

In this example I will call the block you want to appear first first.block, and the block you want to appear second second.block which has an alias of secondBlockAlias.

<reference name="order_items">
    <action method="unsetChild">
        <alias>secondBlockAlias</alias>
    </action>

    <action method="insert">
        <block>second.block</block>
        <siblingName>first.block</siblingName>
        <after>1</after>
    </action>
</reference>