In openmeetings the openoffice documents are first converted into pdf and swf formats before getting dislpayed on the white board. Can we display the contents directly in the office documents form and make the changes in the files that will be visible to the other participants in the conference.
No you can't do that out of the box.
Your question should goto: http://incubator.apache.org/openmeetings/mail-lists.html
to discuss with the developers of OpenMeetings on how to convert documents into an editable format. There is currently a GSoC student working on an alternative to OpenOffice as cenverter, however the goal of his project is not to make the documents editable online.