I have 3 total connections at home (1 primary 2 child), and I can assure you there are no disadvantages to it, rather you would save over 90 rupees in ncf charges...
primary connection ncf is 153 and child connection ncf is 59, plus what channel & bouquets u select.
1 primary plus maximum 3 child connection (total 4) can be installed under one dish antena.