It appears that Mirza Ghulam Ahmad was taught about the Bab and given books to read. That could explain a lot.
that
Interaction with The People of Bahá: A response to Ahmadi Answers
"...... He had a detailed meeting with Mirza Ghulam Ahmad in which not only the glad-tidings of the Advent of the Mehdi (The Báb) and the Messiah (Bahá’u’lláh) were communicated to him but he was also provided with a box full of Bahá’í Books and Tablets for study. In his book Al-Balagh (البلاغ), whose other name is Faryad-e-Dard (فریاد درد), Mirza Ghulam Ahmad also recorded a listing of the subjects in which he gained mastery. This
listing also mentions the Bábí books. This shows that he studied the Writings of The Báb in detail.
In the year 1900 the chief secretary of Mirza Ghulam Ahmad,
Hakeem Noor-ud-Din (who later became the first successor of Mirza Ghulam Ahmad), through letters established communication with the distinguished Bahá’í scholar
Allama Mirza Abu’l-Fadl Gulpaygani in order to get answers to some tough religious questions. Mirza Abu’l-Fadl was residing in Cairo in those days. In response, Mirza Abu’l-Fadl wrote and presented a book titled “
الدُرر البہیة فی جواب اسئلتہ الہندیہ” as an answer. In this book he not only gave detailed and rational answers to those challenging questions but also expounded the message of the Bahá’í Faith.... "
Regards Tony