I miss my granny & grandad, help please?

About 2 years ago my dad & grandad had a really big argument and haven't spoken since. My mum & dad don't agree that I should now go see my gran & grandad, so I've saw them around 3times in the past 2 years. I used to be so close to my grandparents and went round every week. I miss them so much and really want to try sort out the disagreements within my family. Any suggestions of how I can get then to talk? Every answer will be greatly appreciated.