变更合同适用默认规则吗？结辑同志：甲公司与乙公司签订一份桐油购销合同，约定甲公司于当月月底前分期分批向乙公司交货，货到付款，每交付一次结算一次。甲公司第一次交货后，双方依约履行，钱货两清。甲公司第。次交货时，乙公司开给甲公司的收货单上将吨价降低了３０... Is it okay to change the contract to apply the default rules? Comrade comrades: A company and Company B signed a purchase and sale of tung oil contract, agreed to a company by the end of the month in batches to the company B delivery, cash on delivery, settled once delivered. A company after the first delivery, the two sides fulfill the contract, money goods two clear. A company number. Times of delivery, B company to open a company receipt will be reduced by 30 tons ...