Small correction to above post. T Series might as well hold satellite rights of these films as many times in films where there 2 producers involved equally then both take a joint call about selling satellite rights. Like for example when Dharma Productions makes a film with zee studios then despite viacom18 being the partner of Dharma, that particular film goes to zee. So incase of Bhootnath Returns quite possible same happened and now BR Films exiting sony , both would have agreed as star/disney being the new satellite partner.
Also i have noticed that incase of many banners their older film rights r with library companies while for most of the post 2010 library producers themselves holds rights and when broadcasters enter into agreement with a banner they renew new films satellite rights from producers while also acquiring their old films from library companies. This happened incase of recent Eagle Films/Cineyug library which shifted to viacom18, there were most films which were owned by Red Chillies while some came from Shemaroo too like Raja Hindustani.
Incase of GP Sippy / Ramesh Sippy Films situation is even more complicated. Star/disney had all their films thru producer or NH Studioz. Now most old films of their banner shifted from NH Studioz to Goldmines and Sony renewed them, Sholay remains with NH Studioz and still with star/disney, also Taxi no. 9211 and Bluffmaster (2005) now owned by Lionsgate so they will likely b renewed by star/disney or shift to zee and all the post 2010 films still with star/disney. So i am not sure if Sony has agreement with Sippy Films or simply got old films thru Goldmines