Update from one heartbreaking year ago

It's been a year now since the last time we talked to Sophia and got an update on the kids.
Jacob lasted just six weeks at the new foster parent's house. Then he was sent to a psychiatric facility for a month. At the end of that month, the doctors were still not sure what to do - they had not stabilized him, had not fully diagnosed what was going on, and had not developed an outpatient therapy. It sounded like he'd be kept a bit longer.
The foster parent said she would "try" having him back in her house one more time if the foster agency wanted it. We later heard from the foster agency that he was back, but it was only half a sentence and I'm not sure if I am interpreting it correctly.
Anyway. Our last call - a year ago.
We had the baby with us, and we had just driven through Albany's Lights In The Park display. The baby was hungry so we pulled over in a parking lot so I could nurse. We decided to call the foster parent for an update (returning a call from her) while I nursed.
It was 8 p.m., so we figured Sophia would be in bed and the foster parent would thus be free to talk. But no - Sophia was not in bed, and was clamoring at the door while the foster parent tried to talk to us. I asked if we could talk to Sophia, since (as we had feared) no visits had been allowed. The foster parent hesitated. Then she handed over the phone.
We got to talk to her!!!
But it was heartbreaking.
It had been less than 10 weeks. But Sophia didn't remember us very well. She couldn't remember the songs, only that she'd liked them. She couldn't really remember much about us. Her voice was happy, but tentative.
She had moved on.
After that call, I realized it was over.
There would be no visits.
We would never see them again.
And so I forced myself to stop calling during the school day to get updates. I've never called again.
But I drive past the road to their house every single day, to and from work. And so I think about them every day.
I especially think about Jacob. Is he OK?
I've broached with my wife the idea of adopting Sophia several times. But - she's moved on, she doesn't remember us any more, and we should move on.
But a part of me still feels like I've abandoned a little girl somewhere, and I need to go swoop her up into my arms.