Hi Edove and welcome to our forum,
Greg has posted forum responses regarding this in the past and I suggest searching the forum (upper right). According to him:
it's just a matter of getting a ref to the other xdocument:
IXMLDOMDocument x = thisXDocument.(blah.open new document)
And, then you use the x to set the fields int the newly opened document. You can also set one of the fields to be the handle of the existing thisXDocument and have the new form set values in the form from which it was opened.
Hope this helps!
Patrick Halstead
Project Manager at Qdabra