I’m sorry if this feature already exists, but I haven’t been able to find it for GrampsWeb and i think is really cool, specially for long trees when you need show the relation between two members. Both Geanet and Myheritage have a tool that shows you the relationship between two people. I like Myheritage’s more, but here are the examples for you.
basically you have 2 forms to choose both persons
and generates a PDF with the result
On Geanet is similar but more ASCII art. First you need select the first member and then you can click on Calculate relationship
Then you need choose one member or search for someone in the tree
the result is a plain text explaining the relationship between this two persons
If you click on “see” shows an ASCII tree with all relation