TourCMS has two approaches to enable you to work with multiple suppliers:
Each product you load can be assigned to a particular supplier, if you have more than one supplier for a given product you can assign the supplier at the time of booking. Supplier details can be used in documentation, invoicing etc.
If you need to give your suppliers a log in to your system you can create staff login user accounts locked to a single supplier. These users will only be able to see their own products and will be able to update their product descriptions, dates, prices & availability.
The TourCMS Marketplace approach is an alternative way of solving a similar challenge.
Each supplier has their own TourCMS account (which means they maintain their own separate customer database). The XML API can be used to connect multiple TourCMS accounts together onto a single website. Technically all the integration work is done for you already.
This approach is ideal for destination management organisations (DMOs) where the DMO wants to have a great single central website, but doesn't want to manage the individual accounts for each tour provider.
You can have a single TourCMS account that you can provide a login to for multiple-suppliers. However those travel companies who already have their own TourCMS account they can maintain their own account but still feature their products on your website etc