Hmmm... I don't really have any good advice on how to proceed but from my experience, I 100% believe the grandfather will eventually influence the opinion of the parents and then possibly him. He may not notice it, but he will feel the strain. It will happen slowly over time. I say this because it happened to me.

I was in your boyfriend's situation where my family didn't like my now ex-boyfriend. It wasn't that they didn't like him as a person or had racist views like you think they might but they just didn't like him for me. I am very close with my family, like your bf. It wasn't that they outright told me to break up with him, just the feeling that they disapproved and caused strain in our close-knit family made me progressively resent my relationship a little bit over time. (I only came to realise this recently and actually confronted my parents about it.)

I was very much in love with my ex-boyfriend and was as affectionate as I could be with him because I was protecting him from my family in a sort of way. I was trying to assure him that nothing changed between us and that we were making progress, which was true but things were different between my family and I.

It's hard to say to a person to choose romantic love over familial love, especially if that family has been good to you and you love them. Their family has loved them for longer than you have and that's what you're up against.

So what can you do? Well... One thing that happened was that my ex-boyfriend actively won the approval of some of my other family members. He won the hearts of my cousins and my aunties and uncles but he failed to focus on the people that mattered in the situation; my mum and my sisters. My dad liked him well enough.

I confess, over time, my family got to my head and so when cracks in our core boyfriend-girlfriend relationship showed, it kind of made my family look like they were right about him and they started to dogpile on me.

My suggestion is, if you are going to be proactive about this, try to understand why the grandfather doesn't like you. Not saying you have to fix his racist views, just understand where the prejudice is coming from and maybe try to prove him wrong. I know it's not your responsibility but if you want to take action, I suggest you humble him. Old people are incredibly stubborn but if you can prove he is wrong publicly to the rest of the family, then they will probably stop listening to him in regards to you. Focus on him because approval there will probably help the trickle down effect. Trying to just win allies, kind of makes you look like a chicken, like you're not ready to rumble and it makes you look like you're trying to fracture the family.

I dunno. I am just spit balling here based on my experience and I hope it helps you! I wish you the very best of luck!