Last week, the twins' mother Rosdeep Adekoya pleaded guilty to culpable homicide after killing little Mikaeel in a rage after he was sick after a family meal at Nando's.
Mikaeel's father Zahid Saeed, 30, and granddad Ahmed, 65, are now in a legal battle to bring up Ashika, whose life was torn apart by her mother's horrific crime.
Ahmed, a grocer in Kirkcaldy, Fife, said: "My whole family do not believe my son is capable of looking after Ashika with the life he has got. My son and I are not speaking over this."
His son fathered the twins while having an affair with Adekoya, 34. Last week she pleaded guilty to 'culpable homicide'. She will be sentenced next month.
She had beaten little Mikaeel to death but then claimed he'd gone missing, prompting one of the largest police man hunts with thousands of people turning out to search the Drylaw area of Edinburgh.
But she had packed his broken body in a suitcase and dumped it in woods beside her sister's home in Kirkcaldy.
Mikaeel's granddad admitted he had never met the little boy, but now says he wants to bring Ashika up.
Ahmed relived the moment he first saw an image of Mikaeel when police came to his shop.
He said: "They showed me the picture, told me he was missing and asked if I knew him. I told them I did not.
"But he is the image of his father. I told them I did not know his name, my son kept it secret from me.
"I am in my second marriage and I have a daughter who is just two-and-a-half, so it would be easier for her to be brought up with me.
"The two girls could be friends and grow up together."
It is understood Ashika is being cared for by Rosdeep's sister Pandeep and grandmother Harjinder Kular.
Zahid confirmed he is seeking custody.
He said: "She is mine and I will do my best for her."