How did Morgan Freeman and his wife expect to...
...raise the girl normally? Surely they have friends and family. Were they planning to hide her from them all this time (lock her up in a room, hide all her photos and toys from the house)?
Pretend that she's their own daughter in public and hope nobody will notice she looks like the kidnapped girl from months/years ago hanging with the famous police chief who retired after failing to save her?
The only way to make this believable would have been to make the kid a baby and not a 5 years old.