Yes, you can. If the document you want to upload is a contractor document, check our Additional Contractor Documents guide. If the document is a plant, see point #3 in our Plant Document guide. For worker document, go to your workers list and click the 'View' button next to the worker's name. Click the 'View' button next to the client and select Documents table. You should be able to upload additional documents by clicking the 'Add Documents' button. If the document is an equipment request go to 'More' from the left pane and select 'Hazchem'. Select the 'Equipment' tab and click the button next to the equipment to upload a document. And for hazardous chemical, see point #6 in our Hazardous Chemical guide.
In all the above cases, select the proper document category, fill in all requested details and repeat the process as many times as you have to. Another way you can do it is to compress all the documents you want to upload. Add the documents to a .zip file and once the documents are compressed you can upload the file as an ordinary one selecting the proper document category.