Need advice!!!

I need abit of advice as i dont know what to do! My partner does not want to have a 4d scan as we was told by our midwife that having extra scans is very disruptive for the baby. However it has not been proven that the extra scans hurt the baby in any way. My dad was diagnosed with a stage 3 brain tumour last year and he keeps asking me about getting the scan as i think in some way he is scared he wont make it to the babys birth. What exactly do i do?? I have to also consider my partners feelings but its so hard.