As part of the Indo pak community, I was brought up learning that Lady Fatima was the only daughter of the Holy Prophet. However on moving abroad I’ve come across people who guided me to ahadith and comments of classical scholars that he had 4 daughters – Zainab ruqayya and umm kulthum who are always referred to as adopted by the south Asian Shias.
Is this a minority opinion or the truth?

by

The issue of the number of the Prophet's daughters, may God bless him and his family, is an issue that has been the subject of a long discussion among historians
Among them are those who believe that Zainab, Umm Kulthum and Ruqayya are the daughters of the Prophet.
And some of them say that they are the daughters of Khadija from previous husbands, so they are the stepsons of the Prophet, and a third section says that they are the daughters of Khadija’s sister, whom Khadija sponsored after the death of her sister.
Each side provides evidence for its statement.
For my part, I do not rule out that they are the daughters of the Prophet, may God bless him and his family, from Khadija, peace be upon her, but they are not in the rank of al-Zahra, peace be upon her, and this is an undoubted matter.