A method and control assembly are provided for operating at least two lifting devices, such as cranes, in group and normal operation modes. Each lifting device has a control system connected to a control switch, and the lifting devices are controlled through a common bus. In group operation, the lifting devices are jointly controlled through the bus by one switch. To operate at least two lifting devices in parallel, one of the switches is active in the group operation and the remaining switch or switches are passive. To prepare for group operation, normal operation is deselected by all but one of the control switches to release a remaining switch for log-in to the active state for group operation. To prepare for normal operation, group operation is deselected and normal operation is selected at the active switch before the other switch or switches are released for logging into normal operation.