Is it permissible for resident congregants to put forward one of their number to lead the prayer after the traveling Imam, who shortened the prayer, has given the salutation of completion, or must they complete their prayer individually?

There is no need to put forward someone for them to complete the prayer with, and they should not do so for several reasons:

1. The opinion of permissibility is not an obligation or a Sunnah, and it is countered by another opinion of impermissibility. 2. It invalidates the prayer of the congregants according to the Maliki school, as they would be following someone who is himself a congregant. 3. They have already attained the virtue of congregational prayer by praying with the traveling Imam. 4. Because the Prophet, peace and blessings be upon him, used to order the people of Mecca to complete their prayers without putting forward another Imam when he shortened the prayer there.