Business partnership and property business partner died

My son Paul started a business with a man Mr. Rob in South Carolina3 years ago. Mr Rob (a very wealthy / sweet man) owned 600+ acres of land. They started raising black Angus cows. Paul took care of the cows and kept at the property, which was in shambles because it had not been taken care of in such a long time. Him and Mr. Rob became very close even though they were 50+ years apart. Mr. Rob had three children that he was estranged from, not talked to his daughter in 8+ years. Mr. Rob also had a wife that had Parkinson’s disease and was in the on stage of dementia. Paul and daughter-in-law (Stacey) also helped Mr. Rob out with his wife. Mr. Rob became extremely fond of Paul. One time telling me that we had to share our son. He had told Paul and me that he had decided to leave the property to my son. We were both told that a new Will had been drawn up. Three months ago Stacey took dinner over to Mr. Rob‘s house (she would do this every night). There was three houses on the property, Paul and Stacey move into one. When she walked into the house she was concerned, all the lights were off and she heard the shower running. She called out to Mr. Rob a few times and finally went to bedroom and saw him lying on the floor. She called They try very hard to revive him but it was too late paramedics said he had probably been gone for almost 12 hours. The saddest part was if Paul and Stacey weren’t there he probably would not have been found for God knows how long. Paul was so distraught he felt like he had lost his grandfather again. He had the sheriff call the son. It was on speakerphone the first thing the son said was when can we start probate. Not did he suffer, did he die peacefully, now just when can we start probation. Right there that showed me they didn’t care about his father. And within a week the mother passed away. She had last time of her life and couldn’t handle it. That just made Paul and Stacey so sad, and MAD.The son lived 4 hours away but Paul said he was shocked at how fast he actually got there that night. Paul said he noticed that the lights were on in the house all night long. Honestly what I should’ve told Paul was, I know it’s going to feel strange but you need to search that house and find that will. After the funeral the son had told Paul, don’t worry, you’ll be taken care of. And when they told him what he would receive, all it was, was half of the farm equipment. Even though in SC when one business partner dies the other business partner receives the whole business. The business has nothing to do with the Deceased business partners children. Some of the other farm equipment children had it estimated because it went up in price they told my Paul that either he can pay for the other half or they can sell it and he will get 1/2. They had just bought a brand new truck and they had told Paul that he can pay for half of it or they can sell and he will get 1/2.