Thank you to everyone who took the time to read this and leave a comment, let me add a little more info here that is just coming in.
I received an email from a Boston based investigator for the Better Business Bureau asking for me to forward anything we have proving our side of the story - working with the in-laws right now to see if they kept the old paperwork.
As far as having a lawyer in the area, Michael Farraher has offered his services (pro bono) if Casey Movers does move forward with their threats. A number of other notable lawyers have also offered help including Ken White over at Popehat.com.
Thanks again everyone. If you have any questions or advice feel free to email me.