Hi,
>Let's say I have a simple schema defining a Person, like so:
>

><?xml version="1.0" encoding="UTF-8"?>
><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
>	<xs:element name="PERSON">
>		<xs:complexType>
>			<xs:sequence>
>				<xs:element ref="ID" minOccurs="0"/>
>				<xs:element ref="NAME" minOccurs="0"/>
>				<xs:element ref="ADDRESS" minOccurs="0"/>
>				<xs:element ref="CITY" minOccurs="0"/>
>				<xs:element ref="STATE" minOccurs="0"/>
>				<xs:element ref="ZIP" minOccurs="0"/>
>			</xs:sequence>
>		</xs:complexType>
>	</xs:element>
>	<xs:element name="ID" type="xs:integer"/>
>	<xs:element name="NAME" type="xs:string"/>
>	<xs:element name="ADDRESS" type="xs:string"/>	
>	<xs:element name="CITY" type="xs:string"/>
>	<xs:element name="STATE" type="xs:string"/>
>	<xs:element name="ZIP" type="xs:string"/>
>	<xs:element name="PEOPLE">
>		<xs:complexType>
>			<xs:sequence>
>				<xs:element ref="PERSON" maxOccurs="unbounded"/>
>			</xs:sequence>
>		</xs:complexType>
>	</xs:element>
></xs:schema>
>

>
>What would I have to do to define a child entity of PERSON, for example, let's say I want to define PURCHASES for the PERSON. There may be many PURCHASES for one PERSON.

Basically:
Design a PURCHASE element using the same pattern as for the PERSON element above then include it in the PERSON element in the same way that the PERSON element is contained in the PEOPLE element...

BTW the PERSON element looks a bit odd. All the child elements have a 'MinOccurs=0' implying that a completely empty PERSON element is acceptable.

>My main goal here is to be able to have an XML file that has a one-to-many relationship import into an untyped dataset using DataSet.ReadXML() while preserving the relationship.

Why not do this the easy way : build a Dataset and create the schema from that?

Best,
Viv