Perimeter borders around clustered elements

I want to be able to stack several rows on top of each other, which aren't the full width of the screen, and I want to be able to put a perimeter border around all of them as a single cohesive unit.  This would allow the user to create visual boxes to separate important information from the rest of the flow of text.  Unfortunately, borders only work around individual rows, columns and blocks.  It would be helpful to have an edit feature where users could select which "leg" of a border they would like to be hidden/transparent, thereby having the ability to hide all internal borders of stacked elements, so that all grouped/stacked elements would look like they have a single perimeter border around them.