Create service 1 with string property , declare as input, check in service 
Create service 2 and drag service 1 into it . 
Declare property of service 1 to be input in service 2 
Create service 3 with string property and check in it 
Drag into service 2 service 3 
Mark service 3 as dependent and add rule with source 'Service2 - parent ' 
Input of Service 2 is not displayed in the list