Relationships

There is only one correct answer here. The right way to do it in Quick Base is to walk the lookups  down one look up at a time and walk the summary fields up one relationship at a time. You never skip a level.  So if you were summarizing total sales, then you make a summary field between the grand child and the parent, and then on the relationship between the grandparent and the parent you summarize the summary field. 

You never try to add extra relationships directly from the grandparent to the grandchild.  That just complicates your app and also you will not be able to create any summary fields if you use that method.