Extended cinematic universe spoof way.
Har Dil Jo Pyar Karega had Shah Rukh Khan & Sana Saeed appearing as father-daughter duo from Kuch Kuch Hota Hai. Shah Rukh's Rahul is mentally ill post losing his wife & Rani's Pooja Oberoi in the film attracts Rahul's attention as she resembles his dead wife Tina which eventually cures his mental illness, to have him reunite with Pooja in the end.
Heyy Babyy had Dilwale Dulhania Le Jayenge crossover with Anupam Kher & Shah Rukh Khan reprising their father-son characters, Dharmavir Malhotra & Raj Malhotra respectively. Supposedly, Dharamvir is still searching for a suitable bride for Raj & is interested on Vidya Balan's Isha Saini. Eventually Raj signs off after being the convinced by Akki's Arush.
|Har Dil Jo Pyar Karega 
||Heyy Babyy |
|It is the remake of Malayalam film Chandralekha  directed by Priyadarshan starring MohanLal in the lead opposite Sukanya & Pooja Batra.
Anil Kapoor appeared in the cameo as mental patient. The role Shah Rukh did in Hindi.
Sanjay Dutt appeared in the cameo as mental patient in 1998 Telugu remake.
|It is the remake of Malayalam film Thoovalsparsham  which in turn was the remake of Three Men and a Baby .
This has been remade twice in Tamil & once in Telugu before being remade in Hindi.
Anil Kapoor cameo scene in Chandralekha [1997 - Malayalam]
Sanjay Dutt cameo scene in Chandralekha [1998 - Telugu]