A Complex Decision allows multiple Decision Gateways to be connected together to facilitate more complex routing.
Configure Multiple Decisions:
Multiple Decision gateways are configured in the same way as a single Decision, however instead of linking one or more of the Decision Gateways to subsequent tasks, they can be linked to another Decision Gateway.
Configure each Decision Gateway by selecting the required Decision Field and conditions. Instead of selecting a target Step to go to, select the next Decision Gateway.
Before configuring the Decision Gateways please ensure:
At least one preceding Step has a Form Field that can be used in a Decision. These types are:
Dropdown and Option lists
Number and Currency fields
The Decision can be taken from any previous Step in the Flow, but each Decision Gateway can have only one input source.
Refer here to Configure Decisions: http://help.flowingly.net/design-and-build-your-business-processes/decisions