xmp data

I want to add some xmp data to Pdf's.

I saw that you can set custom metadata using:

QP.SetInformation(.,.);

But my question is: Can I set xmp metadata, using a xmp schema with properties, fields and values?

Thanks,

Evert-Jan Modderkolk

thanks that works.

But I was testing it, adding values of more than one schema, then it goes wrong.

So when I only add the values of the first schema to the xml and save it in the pdf als xmp, save the pdf. It goes ok. When I later open that file and add the values of the second schema to the saved file, it goes ok too. 

But when I add the values of the two schemas in one run, no xmp is left in the Pdf.

What can be the reason?