The Supreme Court on Thursday restrained brothers Malvinder Singh and Shivender Singh from diluting any stake in the Fortis Healthcare.The apex court said that the matter will be next heard on October 31.According to reports, in April, the Japanese company had opposed the sale of an 80 per cent stake in the Religare Health Insurance Co. Ltd. to a group of investors led by private equity firm True North and submitted that Singh brothers had violated a prior order requiring them to take court permission to part with tangential assets.