Hi there in 1950s India and Portugal met regarding the status of the Portuguese Indian enclaves. These were happening at the same time as the Indians were meeting with the French regarding returning the French enclaves. When Portugal unlike France refused to negotiate with India and stated that they rather see the Portuguese enclaves as Independent state than part of India the Portuguese were on borrowed time. The first salvo against the Portuguese was in the 1950s when India blockaded Dadra and Nagar Haveli from Daman and in 1954 they were seized by Indian nationalists. So the Portuguese were unfortunately facing a dire situation and worse totally unprepared. Just like the African colonial wars the Portuguese were unprepared but were not facing a enemy with the resources and whereabouts the size of India. The Portuguese army took several years to build up their forces in Africa and the meager Portuguese military situation in 1962 was completely unprepared and ignorant of dangers.
So in summary there was nothing IOTL that the Portuguese can do.