Fernando II and Elisa had a daughter called Alice Hensler, born in 1855 and died in 1941.
Alice was born when Fernando was a widower but before he married to Elisa, which happened only in 1869, when Alice was 14 years-old!!!
About the recognition I don't know nothing. Sorry.
The story concerning this daughter is rather suspicious.
Some pretend she was D. Fernando's daughter, other say she was the offspring of another liaison.
The fact that the child did not carry D.Fernando's name might emply that he did not recognize her (would she be his daughter or not).
Do you know when did Elisa irts came to Portugal ?
If the child was born in 1855, that would be just two years after Q. D.Maria's death.
I know the story of a daughter of Elise living in Parede (or Paço de Arcos ?) next to the famous rock house over the Marginal route. That house was destroyed in the 50/60s.
Another interesting place would be the "Chalet da Condessa" in the Pena Park in Sintra.
It was abandonned for ages and menacing to fall apart.
A couple of years ago it burnt/was set fire to. At the time it was said that an occultist/satanic group used to meet there.
After the fire the local authorities promised to rebuild it, but I never heard anything after.