sharing credit info

my husband farms, he and his sisters own 520 acers jointly. He leases the ground on a 50/50 share basis. As such he inititates credit agreements for his imput costs on his own not as part of the partnership, which by the way is a verbal agreement only. He has one creditor that has turned him over to a lawyer for collection of an account that is well past due. This creditor was informed by my husband that when crops were in this fall he would be paid. Yet he still turned us over, not a real problem yet. This lawyer sent a letter the 12 of Oct. asking for payment in full by the end of the month or actions would be taken. Again the lawyer was contacted and told that when harvest was finished a payment would be made. He said just to let him know when a check could be written. On the 31st, he filed a suit in county court and named the three sisters as co defendants. A complete listing of my husbands charges from the begining of his account with this supplier was attached to the suit. All of this was served to all four parties with a summons to appear. Can this be done, filling against someone who was not a part of the charge account. There were no papers signed setting forth the terms of the account it was set up as a net 10 discount. In the suit it is stated that all four derived income from crops grown on the ground jointly owned and the input from this supplier was the reason such income could be derived. HELP PLEASE!