Intro
The Lahori-Sect of Ahmadis have tried to hide and lie about lots of information on the status of Mahmud Ahmad in the Jamaat.  He was always set to succeed MGA, the inner-circle of MGA and his top team members always knew.  Nonetheless, Mahmud Ahmad was too young in 1908, and since Noorudin was the top ghost-writer, Noorudin became Khalifa, and only after MGA’s widow (mahmud Ahmad’s mom) approved of Noorudin’s Khilafat.

The evidence
SEEARATUL MAHDI. VOLUME 1 PAGE NO 12.
STATED TO ME BY WALIDA SAHBA IT WAS THE TIME WHEN HAZRAT MASIH E MAOUD (MGAQ) was writing Risala AL WASIYAT, ONCE HE WAS WALKING IN THE HOUSE OF MIRZA SHARIF AHMAD (MY YOUNGER BROTHER), HE TOLD ME THAT AN ENGLISH MAN HAD ASKED QUESTION FROM MOLVI NOORUDDIN AS TO WHETHER MIRZA SB HAS NOMINATED HIS PREDECESSOR LIKE EVERY NOTABLE DOES OR NOT.? THEN HAZRAT SB ASKED FROM WALIDA SAHIBA SHOULD I NOMINATE MAHMOOD (KHALIFATUL MASIH ALSANI). WALIDA SAHIBA REPLIED YOU MAY DO AS YOU DEEM IT APPROPRIATE.

The scan work

Conclusions
The Lahori-Ahmadis seemed shocked when Mahmud Ahmad was elected in that sham of election in 1914, it was all in the plan from the very beginning.  Obviously, they lowered the position of MGA and refrained from doing Takfeer only because they knew that MGA was just like his son Mahmud Ahmad, a Liability.