Simple adding offers of different vendors to the panel? Only by using special plugins for IAI Downloader to synchronize offer of almost every wholesale store or supplier.
If you are cooperating with a supplier of product offer and you want to synchronize it with your offer, and update quantity stocks, using the IAI Downloader application, you can create your own plugin to the IAI Downloader.
Plugin for IAI Downloader is an application or script connecting with the supplier data base and generating offer in IOF format, recognizable by the IAI-Downloader application.
Principle of plugin operation is shown on the picture below:
Download the specification of the IOF format. The application, which you will create, needs to generate offer in XML files, structure of which should fulfill the requirements from the specification. Full specs can be found on the website concerning the IOF.