xml merge script

I want a script to merge xml files that their links appear at master xml url. So we have a master xml contain xml links and i want to merge them and save at my server. script must have mini user interface to save the master links and run it from cron jobs. eg. a real link

Master xml link

https://www.zanta.gr/xml/psilos/master.xml

include...

<cardealer>
<lastupdate>2022-04-25T01:04:01+02:00</lastupdate>
<include>https://www.zanta.gr/xml/psilos/0.xml</include>
<include>https://www.zanta.gr/xml/psilos/2.xml</include>
<include>https://www.zanta.gr/xml/psilos/3.xml</include>
</cardealer>

I want to save at the script all xml master links and run it from cron jobs of my server.
Script will merge all links included at master xml links and save them at my server.
every master link have a different file saved.