Mumbai, Oct. 11 -- The Shapoorji Pallonji Group on Friday pressed for a public listing of Tata Sons that the Tata Group holding company is trying to resist, invoking the ideals of transparency espoused by its founder Jamsetji Tata. An initial public offering (IPO) would be a major relief for the debt-ridden SP Group, which holds 18.37% in Tata Sons. The public statement from SP Group came on a day when the Tata Trusts, the majority owner of Tata Sons, held a meeting of its trustees. "The public listing of Tata Sons is not merely a financial step-it is a moral and social imperative," SP Group said. It would unlock significant value for over 12 million shareholders of listed Tata companies, who are indirect shareholders of Tata Sons, it said....