From the threads that I'm reading dialysis is one reason for denial. Actually, when I submit my interest to sponsor online last October 14 I only apply my mother because medical examination for my father will be an issue. No idea. I just found out recently when cic emailed the invitation that both parents will be considered in the application although my father is non accompanying.
No he hasn't bee denied for visas. He has tourist visa before. He started his dialysis 2 years ago
Anyways I will give it a try and will go from there. Maybe I could write a letter to cic that I only want my mother to be sponsored? well I don't know if that works??