if i understood your question right, u want to have the same channel watched on the other 3 tv's which is also being watch in the living room ??
If so then all you gotta do is on the RF output conenct that upto the lead that goes to the other 3 tv's.
Well used to years ago. . cant see why it would change. . the only reason i can think of it not working would be that your cable is screwed directly onto the coax socket on ur set top box, which might not as a master input for both coax and RF.
Other way u cud try wud be to get an adapter from coax to RF and then use the Rf socket http://www.maplin.co.uk/Free_UK_Deli...r_29525_v2.htm
i wud assume you would still recieve the same channels If not then its a utterly STUPID design and function! and quite frankly a waste of harware!
Or split the signal have one cable go into the coax, and another cable go into the RF input
with the adapter.