Dharma Productions had agreement with sony (most probably as Dharma Production films were distributed by YRF) in late 90s, early 2000s which lasted till 2009 .... Later on Dharma Productions ended distribution agreement with YRF and Star India (Fox Star) came onboard as co producers as well as satellite partner bcoz they acquired rights of self produced films as well as thru agreement with UTV Motion Pictures got other Dharma Production films, even older Dharma Production films shifted from sony to star india.
Later around 2014 or 15 all these films shifted to viacom18. In following years Dharma Production co produced many films with Zee Studios whose rights r currently with zee network but may expire later
Same thing happened with Red Chiilies all their films were with star/disney in 2000s including those produced under Dreamz Unlimited Banner by SRK. Only exception was Om Shanti Om which premiered across many chs. Later around 2012 or 13 these films shifted to viacom18 and later in 2013 Red Chillies entered into new films agreement with Zee Network, Zee never got hold of their older films library as these reamained with Viacom18 as per agreement. Now both these agreements most probably expiring soon. In around 2014 Red Chillies had even acquired rights of Cineyug films which recently shifted from sony/zee to viacom18.