Jagya could have convinced ganga that mannu needs mother more than the hospital. Atleast until school.
Shiv could have convinced anandi to first try for a biological child while still caring for the orphans.
The grandparents usually pamper than give proper upbringing.
Ira's desire to have a biological grandchild is natural though she maybe unaware that Shiv himself is not her biological child. Once she knows the truth, she may stop craving for that pleasure.