Central Govt Patent: What is the inventor entitled to?

My father was a scientist with a central government research institution. His most successful invention was patented just before his retirement. He is the primary inventor and his name features first in the patent. After his retirement, the technology from the patent was transferred to multiple pharmaceutical companies including a spin-off company,. The products have been received very well in the market, over the past decade or so. The institution has received royalty from the companies. The institution never informed my father about the success of his patent, and never acknowledged him in press releases or newsletters. Credit and awards have been given to his juniors. Some of my questions are: What is my father entitled to? What steps can I take on his behalf? Is there any law that I can avail of?