See projects rolled up in a program gantt

Apologies in advance if this has been answered before - and I imagine it must have been since it seems a very obvious and primary requirement for managing projects in a business. Still, for something this fundamental I just can't understand why I can't see anything in the solutions centre or a search here in the community.

We are an architecture firm with a bunch of projects in Smartsheet using gantt view. Each project has stages (Schematic Design, Design Development, Documentation....).

We need to see these projects rolled up and represented in gantt form on one sheet. We also need them on one sheet but by project and stage.

This is so we can see the timing relationships between projects in this 'helicopter' view of the overall 'program'.

We currently have a klunky solution that requires formulas in special hidden columns in each sheet that are then acessed by reports. But its klunky and and demands that users copy/paste and not use Insert for rows when they make their project tasks. Invariably they forget to not use insert, and the forumulas don't copy.

Surely there is a readily accessible solution? 

Thanks in advance.