Okay, little update for you:
After a few days of just waiting for the weekend to visit the Goths, Mortimer suddenly called Zoe and wanted to come over. She has previously talked to him in the park, and apparently he did consider believing her. So he told them to find more information in the library of Willow Creek. Interestingly, Mortimer's visit occurred just a day after an alien had stepped through the wormhole in their lab.
Zoe and Connie went there as David had to sleep. Zoe read through several history books in search of anything about Bella Goth and, because of what happened in Connie's universe, Arlo Bunch. While Connie constantly kept in touch with Mortimer to tell him what they found out.