libxml: How to add sibling nodes to root node

[217sari739bohlken601]

I'm implementing a function doing xml signature with libxml.How could I add sibling nodes to root node?original xml:\[code\]<?xml version="1.0"?><object>...</object>\[/code\]what I want:\[code\]<?xml version="1.0"?><object>...</object><additional node>...</additional node>\[/code\]After parsing, the object node will be the root node, so I can't use xmlNewChild.What function should I use to achieve what I want.Thank you.