Related documents can be attached to the share register when it is created and afterwards. All information and related documents are in the share register under “Company information”.
Firstly, go to "Shareholder Register" in the left menu. Then click the "Company information" tab and then click the three-dotted icon (···) and select "Edit company information".
Then scroll down to the “Documents” heading. Click the box or drag and drop files into it to upload documents. Finish by clicking the "Save" button.