Transfer of company shares

Dear Sir, My parents, had 3 sons. And my parents were joint owners of shares of a company. My eldest brother passed away in 2016, he was not married and also had no kids. After my dad passed away in 2018, the shares were transferred to my mum. My mum back in 2019, did a settlement deed and said upon her demise I would become the sole owner of the shares. A year after my mum’s passing I wrote to the company that handle the shares, I sent the settlement copy requesting them the procedure for transmission. They told me I need to apply for a succession certificate and also get a no objection from my other brother. I told them if my brother knows about this why would he give me an noc for free, either he will try to get half the shares or he’ll ask for monetary compensation. Their reply was it’s my look out. And also since I already have a settlement deed, why would I need a succession certificate. And my mum’s wishes are very clear. So, is there a way I can transfer the shares with out involving my brother. I also want to add, my brother he does not live in India, he’s a US citizen, meaning he owns a US passport. The only reason he managed to get his name on legal heir certificate was using his expired Indian passport. So another question is being a US citizen, does he have rights in India in owing shares or property. Thanks for your time, Thomas