You can not create one master Gantt chart by selecting the projects to view. You can copy and paste the task from one project into another to create one large project file. Or you can view multiple projects on one Visualization page. 

Viewing Multiple projects at a time

You can use the "Visualization" feature to see reports based on multiple projects at a time. 

Please use the following steps:

1. Go to the Gantter home page. 

2. Select more than one project on the home page, the button at the bottom-right of the screen will change to show the visualization option.

3. Click on the button at the bottom-right of the screen

4. Once the visualization has loaded, you will be able to use the tabs to see different reports based on the projects you selected.

5. In the top menu you can see the option Task view, whether multiple projects working with different tasks with the same resources you will be observing

All Visualizations graphs can be edited and created once a subscription is purchased.