Let's start out with the undrafted free agent college players who have already agreed to terms with the Dolphins after the draft:
Remember...The Dolphins will be signing far fewer of these this year because they simply don't have enough roster space to sign 25 undrafted guys as in years past. Indeed the most undrafted players the team could bring on is 10 and that would bring the roster to the NFL mandated 90-man limit.
Obviously, the Dolphins could add more UDFAs but would have to start cutting players currently on the roster -- something I would recommend because I don't get the logic of having proven vets (who have only proven they're not good enough) instead of adding a young guy who is probably already as good and might actually surprise somebody.