Dallas had a 3rd round grade on Dawkins on draft day, I know they whiffed badly on that one but they are not a lot of talented free agent Dlineman out there. Montgomery and Dawkins are probably the most talented free agents out there and Dallas has two practice spots and one roster spot available. Why not just bring in two D Lineman in just for the heck of it? Who else is better out there? Take into account Dallas will probably cut Lemon once Durant, Holloman, and Lee come back so that would open up 2 roster spots on the active roster. I really don't expect much if anything from either Dawkins or Montgomery to be quite honest. With that said with there will most likely be two active roster spots with Lemon getting cut and Dunbar getting put on IR and an additional 2 practice squad spots so there will be 4 people that should be brought in.
I would offer Everrette Dawkins and Tyler Wilson a practice squad spot. I would then sign Montgomery and DC Jefferson to the active roster and see what they could do. If Montgomery and Jefferson are not humbled by their recent football inactivity they can simply be cut like Marvin Austin was with no damage done to the salary cap. if the line comes on for Montgomery, he could provide quality depth at DE and allow Wilber to stay at SLBer where he looks like a much better player.