IOTL Rohingya leaders came to Jinnah to ask him to make the Muslim-majority areas of Burma as parts of East Pakistan. Jinnah accepted, though what if he had declined?
Hardly very well. Burmese government would had punished Rohingyas about such traitorhood. Even in OTL relationships between Pakistan and later Bangladesh were and are still very bad.
OOC: had that happened there would have been no E Pak, at least not as a province of Pakistan, Jinnah and the AIML always wanted two countries, this way it becomes feasible.
A country where part A is 1,300 miles away from part B? ? Probably citizens of each part are going to think the other citizens are being favored, the average citizen in part A is going to know few if any people in part B, etc, a lot of problems.