Hi Robert, I would suggest applying a custom text field to define the type of work in each task in each (sub) project. For example, “MechAssy” or “BuyOut” or “FinalInsp”. Then in the View ribbon, make a new Group definition to Group By Project, Then By (your new custom field). Un-check both “Show summary tasks” and “Maintain hierarchy” in the group definition. If you are going to combine multiple sub-projects into a single master project, then you will want to be sure that exactly the same custom field is used for this definition in all sub-projects, “Text3” for example.
Unfortunately, the roll-up of group-by summary dates (i.e. start and finish) is a little flaky for master-subproject arrangements (At least in MSP Pro 2010, which I continue to use). Project blanks-out the rolled-up dates after an edit, but the undo button will restore them.
Despite the title of your post, your question mentions nothing about logical links between projects or between master- and sub-projects. Those are a completely different – and troublesome – animal.