n Open for just over one week, Liz Cohen’s new p.r. firm, Liz Cohen PR and Consulting, was short-lived. Cohen announced her plans to merge with Weintraub/Siegel PR on Monday. But the newly formed trio is still scrambling to come up with a name. “Weintraub, Siegel and Cohen sounds too much like a law firm,” said Cohen, whose focus at the p.r. triumvirate will be fashion.