OTTAWA—Opposition members shut down a parliamentary committee hearing Wednesday after the Liberal government once again refused to let a political aide appear to answer questions about the now-dead deal with WE Charity. Members of the House of Commons’ ethics committee had asked Amitpal Singh, a senior adviser to Finance Minister Chrystia Freeland, to testify after a majority of MPs passed a Conservative-sponsored motion to that effect last week. The motion allowed Prime Minister Justin Trudeau to appear before the committee in his place. But the Liberal government, which has ordered political staff not to appear before committees, deployed Associate Finance Minister Mona Fortier to instead appear for Singh, who worked for Bill Morneau when he was finance minister. It was the second time a minister appeared instead of a ministerial aide after government House leader Pablo Rodriguez took the place of Trudeau’s director of policy earlier this week. While the …