Unfortunately for Tewi, the curse had made her incredibly gullible, something that her companions had definitely used to their advantage.  Of course, her addled mind was completely unable to realize just what her "friends" had convinced her to do, even when she was doing it.  So it was no surprise to anyone that she simply smiled and followed Momo along, not realizing anything suspicious about why she would need to be registered as a slave in order to work for the innkeeper.  "That sounds good, Momo," she said innocently, still playing along.  "Let's make this all official so I can start working here and earn us a longer stay."