SQLRemote: Implicit synch of connected objects
It appears that this can be done with subqueries inside publications. 

From documentation: 

CREATE PUBLICATION SalesRepData (
TABLE SalesReps
TABLE Customers
   SUBSCRIBE BY rep_key
TABLE Contacts
SUBSCRIBE BY (SELECT rep_key
   FROM Customers
   WHERE Contacts.cust_key = Customers.cust_key )
);


This would catch all customer contacts for sales rep's customer. 

Quiet important seems to be, that this needs to be updated once the connection has been updated -- e.g. a sales rep is getting new customers. This needs to be done with an BEFORE trigger for UPDATE/INSERT/DELETE.