1. When Sid met Ayesha first time he felt some connection with her and told Roshni that it felt like she is from a good family and there is some connection.. Now, he was very close to Shiv, may be Shiv's atma gave him that instictđ
2. Even Roshni have a very strong bond with Ayesha, can be blood relationđ..
3. Ayesha calls DD 'Badi Maa'.. Now that can come out to be coincidence..
4. If they want to keep Ayesha in Patel house or in the show w/o SidNi adopting her (b'coz the kid is cute and they can use her in some family scene in futuređ), the only way is she being Shiv's daughter. Shabnam maynot be but Ayesha can be his daughter..
5. All the Gandi khoon dialogues wouldn't have happened if she is someone else's khoonđ..
6. Shiv surely have some past, he was being chased by goons when Sid found him.. So, there is something fishy..
So, a major part is Gafoor's plan but there is high possibility that the kid is Shiv's child.. If Shiv was a main character, they would have made his image clean towards the end. But since he is not important in the story and DD is important, they can bring in this angle to gain sympathy for DDđ