XSLT FILTERING - PHP FORM

[pedigree]

First of all, I have to use XML and 3 XSLT. The first XSLT will be used to select some elements of the XML, the 2nd one will be for removing the selected elements and the last one must be used to show the actual selection.My problem here, is that I don't know how to make my XSLT "dynamic". I don't know how to modify the filtering options based on the user's command.In the end, we have to use a PHP or HTML file to show that our XSLTs are working.