I would like to see the addition of a global grid in addition to the grids that are based on the initial piece that was laid. Initially I thought that was what the ctrl key was for, but I was obviously wrong.

We should have this choice, maybe even as a default, whenever a new piece of is build.

That way two separate structures could merge at a later point, which is currently not realistic.

Planet Zoo is a good example who to do it. (Although that editor can cause severe headaches in different areas...)

if we can toggle this on and off, i'd be for it.  I wouldn't want it always on.  use it to set your first piece lined up how you want,  your wall or foundation, then turn it off as the rest have angles preset, don't need the grid for that.