SLIGHT SPOILERS AHEAD:
So, am I wrong in thinking we haven’t seen an explanation of what happened with Etta when she was kidnapped?
After watching this week’s episode, I think it’s likely that Peter leads “resistance Observers” (like September) take the young Etta back to Peter and Olivia after the resolution of “The Bad Observers” conflict.
Or possibly even take Etta to an alternate universe to which they all escape.
Very much like when Walter took Peter from the alternate universe.
Just a thought.