I manage to solve this problem :
what I did:
1. add a new instance variable to the other family : onewayhelper: 0 default
2. add a new sprite: ONEWAYHELPERSPRITE with a instance variable onewayhelper:
this sprite will be positioned at the nodes that you want one way behavior: with the insance variable of 1 and 2. you can't go from 1 to 2.
modify this events like this: