When you use the same account to file her return, then her return overwrote his return & you cannot get it back.  With the Online version you must use a separate account for each person.

How do I start another return in TurboTax Online?

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...