Looks that question was from a spammer (had a hidden link in signature, since deleted) but thanks for jumpin' in to help! 

I suppose one could gang together as many window units as one would like, but two or three is probably the practical limit from a structural standpoint.

Here is a three-gang of windows with one header, utilizing the recent advanced framing options:

Version 1.0.0 - 05.10.2025
- Enabled an edge material/texture for LSL rim boards.
- Fixed a bug with diagonal deck boards for large aspect ratio decks/floors.
- Fixed a number of misc. minor bugs.
- Added the following steel deck profiles: 2.0D, 3.5D, BCD-36, N3CD-32, W2CD-36, W3CD-36.



The floor opening tool and the MPC wood trusses are still pending so I really don't want to call this Version 1.0.0 but I also really need to get some bug fixes out the door and some other minor updates and I've run out of letters in the alphabet.  In the next couple of weeks I'm hoping to devote all of my time to these two big items and see if we can actually knock them out this time.

I'll be the first to admit that I am spread a bit thin with all of these plugins.  I've been bouncing back and forth between the Wall and the Truss plugins for the last couple of months but now the Floor plugin needs my attention.

Version 3.9.9b - 05.09.2025
- Enabled backward compatibility with existing windows (advanced framing options).

!!! CRITICAL BUG FIX !!!
When I rolled this out last night I forgot to add exactly one line of code which would have made sure that all previous windows were backward compatible with the recent inclusion of the advanced framing options.  Please update your installation to this latest version if you have recently installed Version 3.9.9.  My apologies for this major inconvenience and my somehow missing this with the initial release of this new feature.

If I were your friend and had to give you just one solid piece of advice - insulate the underside of your floor.

Tutorial 70 - Advanced Framing Options for Windows (11:03 min.)

Version 3.9.9 - 05.09.2025
- Updated the Connect Corner tool to work with non-orthogonal walls.
- Fixed a bug with the in-wall column tool for gable walls.
- Enabled Advanced Framing Options within the window module.
- Added the Advanced Framing Options parameter within the Windows tab of the global settings.
- Fixed the callout for right handed slider (OX) windows.
- Enabled zero stool extensions and zero stool projections for all window casing options.

You're thinking in exactly the right way—treating your initial small home not as a "starter" or "temporary" structure, but as phase one of a master plan for a long-term home. Many people retrofit additions to homes never designed to be added onto, which leads to disjointed layouts and expensive rework. You have the rare opportunity to avoid that. Hire an architect or residential designer now to design the entire future home, even though you'll only build part of it initially.

Most people try to save money with cheaper versions of expensive things. But the real trick is to cut out anything that's unnecessary work. Flat, square, simple. Durable, not fancy.
Focus on systems that do multiple jobs at once — like SIPs (structure + insulation) or plywood (sheathing + wall finish). Use what's fast and good enough.