Unique Situation

So what I'm going to ask requires some backstory information. Before I was born, my grandfather quit speaking with his mom (my great grandmother) and his siblings. He is one of 12 children and he hasn't talked to them in over 20 years. I know I met my great grandmother and his two sisters once, but I don't really remember them. My mom was also never really allowed to have a relationship with any of them. Fast forward about six months ago, my grandfather quit talking to my parents, my brother and I. He didn't attend my brother's wedding in February and I doubt he will attend my wedding next year. The reason he quit talking to us is because my parents technically fired him from his job. My dad last his job approximately two years ago and at the time my grandfather's boss was looking to sell his business. My grandfather was an employee for the company for about 40 years, but he didn't want to buy the company because he is almost 70. He knew my dad needed a job so he suggested that my parents buy the business. My grandfather trained my dad and brother for about six months then the owner of the company sold the business to my parents. Everything was fine at first until my grandfather started making ridiculous demands. He also seemed very jealous of how successful my parents were with the business. They gained a ton of new customers. The old owner didn't really do any advertising, but my parents created a website and Facebook page, bought shirts and hats, made business cards, and advertised in the paper. My parents were quickly getting fed up with my grandfather. He was saying truly awful things to my mom so finally they decided enough was enough and they let him go. He kept one of their credit cards for the business and continued using it. He also kept keys to one of the trucks they use for the business. He told them if they wanted the credit card and keys to come to his house to pick them up. He pulled a gun on my dad and brother so they immediately left. I don't think there is really any way that our relationship with him is going to improve. My mom recently reached out to one of his sister's. She has been so sweet to my mom. We were going to have Easter with the entire family, but because of Covid that didn't happen. My mom has always wanted to get to know her family since her father never let her have a relationship with them. I would love to invite them to the wedding, but I don't want it to seem weird since I don't actually know them or like I'm inviting them as a way to get a gift or something like that because that's not at all the case. Do you think it would be okay to invite this side of my family enough though I don't actually know them?