Closed office

Where to start...

10 years ago opened office in another state...only number shared was FEIN...The managers there, had full range of payable, receivables, invoicing, all insurances, workers comp, unemployment, commercial, vehicle... Monthly, we at the parent company would receive all month end information as well as payroll and process all paperwork  on 941's and year end Partnership returns. Never had any signed agreements...good faith and hand shakes... Now after the Managers in the other state decided to go out on their own...not buying the business....never sending any percentage of income...still  have some of the equipment that was originally from the parent company, opened up credit cards...without permission or authorization from parent company....are now asking for  half of the debt they incurred, opening up credit cards in personal names...with the Parent companies name...are asking for 1/2 of debt.... Am I legally responsible? Is it worth a lawyer? What are my rights? What are their rights, technically they were employees, drawing payroll checks and issued W-2 forms.