question on filtering a one-to-many relationship

Hi all,

Just to make my use case clear I quickly came up with a simple example showing
my use case.

I need to write a function that enables me to return all <person>'s  which
have at least 1 child that MATCHES a specific search string.

          persons/person[matches(upper-case(children/child/name),
upper-case($searchString))]

Above expression does not work as the matches can only handle a single string
as input and not a sequence of names.  So I was wondering what would be an
elegant way to solve this puzzler?

Kind regards,
Robby Pelssers


<persons>
  <person>
    <name>Robby</name>
	<children>
	  <child>
	    <name>Lindsey</name>
	  <child>
	  <child>
	    <name>Valerie<name>
	  </child>
	</children>
  <person>
  <person>
    <name>Audrey</name>
	<children>
	  <child>
	    <name>Linn</name>
	  <child>
	  <child>
	    <name>Tamara<name>
	  </child>
	</children>
  </person>
</persons>