Intro
MGA basically stole Sir Syed’s ideas.  In fact, the name “Ahmadiyya” came from a book that Sir Syed wrote  Al Khutbat al Ahmadiya (1870), in reply to Muir”s “Life of Mahomet”  .  Sir William Muir’s “Life of Mahomet” (available online) made some wild allegations against the Prophet Mohammad (saw). Syed Ahmad was greatly disturbed and pained and prepared to write a detailed response in the form of the book “Khutubat-i-Ahmadiya”. He planned to collect research material in England during his trip to England. Syed Ahmad had to endure many financial difficulties for the translation and publication of the book in England. He later expanded upon these ideas in the form of “Tasanif-i-Ahmadiya”. Maulana Moudoodi declared this book as the first major scholarly work on the life of Prophet.

See—http://www.sirsyedtoday.org/books/?cid=64

Further, MGA and Sir Syed seem to have began to compete for followers, obviously, Nooruddin chose MGA over Sir Syed, Ameer Ali, however, he chose Sir Syed over MGA, and there was another guy, Shaikh Abdullah, he chose Sir Syed over MGA in 1891, since MGA seems to have went crazy and claimed to be the messiah.

The reference work
In this book:

A Woman of Substance: The Memoirs of Begum Khurshid Mirza, 1918-1989

By Begum Khurshid Mirza

https://books.google.com/books?id=CWZX1eIUDZoC&pg=PA28&lpg=PA28&dq=Shaikh+Abdullah+and+Noorudin&source=bl&ots=EcabvSVgB0&sig=BIGbSW85fmRIR-sQDNfzTeepVao&hl=en&sa=X&ved=0ahUKEwi9nePKwYvTAhVEyVQKHTyJCEIQ6AEIRTAL#v=onepage&q=Shaikh%20Abdullah%20and%20Noorudin&f=false

It is written on pages 27-29 how Shaikh Abdullah quit Ahmadiyya in 1891 and went and joined Sir Syeds school of thought.

Noorudin’s death
It is stated in this book that when Noorudin was on his death bed (1911–1914), he asked for Shaikh Abdullah to visit him.  However, the Shaikh refused….nonetheless, the Shaikh would send money to the widow of Noorudin thereafter.  It is also stated that Noorudin wanted Shaikh Abdullah to be the 2nd Khalifa of Ahmadiyyya….not Mahmud Ahmad.

The 1930’s
Shaikh Abdullah seems to have interacted with Ahmadiyya again in the early 1930’s..as he worked with Mahmud ahmad on the All India Kashmir Committee….in fact, he seems to have helped Ahmadis do tabligh in Kashmir in those days…more to come on this.

Additional data
In the two biographical works on the life of Noorudin (english) books, this data is given:

1—-“”””Khan Bahadur Sheikh Abdullah Pleader: Formerly Thakur Das, he accepted Islam at the hand of Maulana Sahib. He was from Poonch. He had been under the deep influence of Maulana
Sahib and got his education in medicine from Hakeem Sahib and, because of the patronage of Hakeem Sahib, he was able to attend the Aligarh University for higher education and, later, he did attend his education in law.”””  (see HAKEEM NOOR-UD-DEEN (Khalifatul Masih I) ——— The Way of the Righteous —— By: SYED HASANAT AHMAD, online edition, https://www.alislam.org/library/books/noor-ud-deen/hakeem-noor-ud-deen.pdf. retrieved on 4-7-17, see page 150)

2—-“””Sir Syed Ahmad Khan founded an All India Muhammadan Educational Conference in 1886 in order to create an urge and thirst for advanced education among Indian Muslim youths who
were left behind in this field. Hakeem Sahib was always in support of any movement that would advance the cause of the Muslims in India and, he was therefore the first among the people
who founded the educational conference and gave financial support. During the time he was in Poonch rendering medical treatment to the son of the Rajah of Poonch, he produced another
remarkable feat. In addition to the writing of Fasl-ul-Khitaab, he converted Thakur Das, a Brahman man in his service, to Islam. Hakeem Sahib sent this young man, Thakur Das, for advanced studies to Jammu and, when he returned, he embraced Islam.  Because of the support and assistance enjoyed by him, he was able to complete his education at Aligarh University and, later, he was known as Khan Bahadur Sheikh Abdullah, advocate of the
High Court.”””” (IBID, see page 72)

“””When Hadrat Khalifatul Masihra was seriously ill after his fall from a mare he saw in a dream that someone had put a rupee in his pocket. He interpreted this as meaning that a son would be born to him. The dream was fulfilled on November 18, 1913, when he was blessed with a fifth son whom he named ‘Abdullah.”””  Hadrat Maulawi Nur-ud-Dinra Khalifatul Masih I by Muhammad Zafrulla Khan, 2006 ISLAM INTERNATIONAL PUBLICATIONS LIMITED, online edition, see page 263) (Zafrullah Khan did not give a corresponding reference, he was terrible at reference work).

The Editor of the Curzon Gazette wrote:

“”””We had not only known the late Maulawi Hakim Nur-ud-Dinra personally, we were on
very intimate terms with him in Jammu for several years. We met every evening. He was
very good-hearted and benevolent. He possessed a keen sense of humour. He was tall,
handsome, fair-complexioned, and wore a thick beard. He supervised the state schools and
hospitals diligently and honestly. He enjoyed a large salary, the greater part of which he
generously devoted to the maintenance and upkeep of deserving students. Throughout his
life he provided for hundreds of poor students. Shaikh ‘Abdullah, a young Kashmiri Brahmin,
became a Muslim through his teaching. He supported him and paid for his schooling and
education till he became a lawyer and set up in practice at ‘Ali Garh. Shaikh ‘Abdullah took a
keen interest in the education of women and started the publication of the journal Khatun
from ‘Aligarh.

Thus Hakim Nur-ud-Din ra was a living example of true benevolence. He had two great passions, promotion of the welfare of indigent students and the collection of rare books. All his
large income was devoted to these two purposes. He was very humble and courteous.
He performed all his duties righteously. Those who worked under him were well pleased with
him and never had any grievance. He was an erudite divine and a great scholar; he possessed
great proficiency in Arabic. During his leisure hours he gave lessons in Bukhari and Muslim.
He had a profound understanding of the faith.”””””  (IBID, see pages 309-310).