Assuming each of you has 60000 UA miles, it is better to redeem one round trip ticket for one person from one account. A round trip ticket allows one free stopover and two open jaws but these things are not allowed on one-way tickets.
For example, you may want to redeem LAX-FRA-BRU-LAX as one ticket with 60000 miles. The destination of your ticket is BRU and there is a stopover at FRA on your outbound flight. It saves you a one-way ticket. Even more, you may want to have LAX-FRA // BRU-MUC-LAX or LAX-FRA // BRU-MUC // SZG-LAX. Use your creativity!