Reusing XSD information for full and update record

[Greg]

Hi everyone!

I want to exchange full and partial records with XML. Example:

<person>
<id>12</id>
<lastname>Miller</lastname>
<firstname>Bob</firstname>
</person>

Another type of element to change that record's person's first name:

<personUpdate>
<id>12</id>
<firstname>John</firstname>
</personUpdate>

So in the full record, all elements must be present, while the update
version only has to contain the id, and everything else is optional
(well, there should be at least one element).

In the schema definition, I don't have to have different element types
for a full record and an update record, but I'm doing that right now,
with the same sequence of child elements (id, lastname, firstname), only
that in the update version, there is minOccurs=0 maxOccurs=1 for
everything but the id while in the full version both attributes are 1 to
make all elements mandatory.

Is there a better way to express this? Whenever fields are added,
removed or modified I have to edit .xsd files in two places, the type of
the full and the update record. This is error-prone.

Thanks in advance!