Merging and sorting multiple XML files

Hi,
I've been trying all day to do this but I think I'm too much of a
newbie...

Here is the thing:
I have multiple xml files that I need to merge and then sort some data
in them.

Here is a sample of two xml file:

The first one

<?xml version="1.0"?>
<PreVCD>
        <component name="stack">
                <subpath path="stack_environment">
                        <variable var="ins" symbol="!" wireonbus="1"/>
                </subpath>
        </component>
        <dump>
                <time t="0">
                        <data>
                                <symbol sign="!" value="0"/>
                        </data>
                </time>
                <time t="10">
                        <data>
                                <symbol sign="!" value="1"/>
                        </data>
                </time>
                <time t="25">
                        <data>
                                <symbol sign="!" value="0"/>
                        </data>
                </time>
        </dump>
</PreVCD>

and the second

<?xml version="1.0"?>
<PreVCD>
        <component name="stack">
                <subpath path="stack_behavior">
                        <variable var="i" symbol="@" bussize="1"/>
                </subpath>
        </component>
        <dump>
                <time t="0">
                        <data>
                                <symbol sign="@" value="0"/>
                        </data>
                </time>
                <time t="5">
                        <data>
                                <symbol sign="@" value="1"/>
                        </data>
                </time>
                <time t="10">
                        <data>
                                <symbol sign="@" value="0"/>
                        </data>
                </time>
                <time t="20">
                        <data>
                                <symbol sign="@" value="1"/>
                        </data>
                </time>
        </dump>
</PreVCD>



The ouput should look like:

<PreVCD>
        <component name="stack">
                <subpath path="stack_behavior">
                        <variable var="i" symbol="@" bussize="1"/>
                </subpath>
                <subpath path="stack_environment">
                        <variable var="ins" symbol="!" wireonbus="1"/>
                </subpath>
        </component>
        <dump>
                <time t="0">
                        <data>
                                <symbol sign="@" value="0"/>
                                <symbol sign="!" value="0"/>
                        </data>
                </time>
                <time t="5">
                        <data>
                                <symbol sign="@" value="1"/>
                        </data>
                </time>
                <time t="10">
                        <data>
                                <symbol sign="@" value="0"/>
                                <symbol sign="!" value="1"/>
                        </data>
                </time>
                <time t="20">
                        <data>
                                <symbol sign="@" value="1"/>
                        </data>
                </time>
                <time t="25">
                        <data>
                                <symbol sign="!" value="0"/>
                        </data>
                </time>
        </dump>
</PreVCD>


This means that the node should merge in component and in time and time
must be ordered.

Thanks in advance... this would save my day !! (and night ...)

Herve