I have an application that gets an complex dataset (more than one relating 
tables) from the database.

For displaying the data I want to restrict the data of the mastertable 
(i.e. Name like 'A%'). 

How can I get the datasets complete XML with regards to this restriction? 
Is there a simple solution?

The only long one I can imagine is:
Create new dataset2
Filter Mastertable and merge it to dataset2
Get Childtable via datarelaten and merge it ...
...
GetXML() of dataset2.