If you’re not using Programs or Strategies at the moment, you could just repurpose the Strategy structure and treat that as your main project. Then link your sub-projects to it using the standard association functionality. You can do the same if you’re not using Outcomes. To be honest, this usually looks a lot cleaner out of the box. You can build roadmaps at the Strategy or Outcome level, so from a reporting point of view it actually works quite nicely and gives you a good rolled up view. There are also a few other ways of doing, for example, you could create a master project and use buckets inside it to represent sub projects but that comes with quite a few drawbacks. It doesn’t really work well from a financials perspective and roll ups aren’t fully there. You can also link things via external dependencies (native functionality) or use custom attributes but again, it really depends on what you’re trying to achieve and how you want the end result to look. So yeah, there are quite a few options, it just depends on the goal and which modules you’re actually using.