BBC don confam say one newborn pikin wey dem bin find for street earlier dis year, na di third pikin wey di same set of parents go troway.
DNA tests wey dem show for East London Family Court bin show say, "Baby Elsa" get elder broda and sister wey dem bin find like dem find her for 2017 and 2019.
Even though di Metropolitan Police don dey work on di mata well, dem neva find dis parents dem.
Di BBC abd PA media bin get special permission from court to tok about di sibling link and say di pikin dem dey black.
Judge Carol Atkinson say di tori get "great public interest" as e no dey very common to abandon babies for modern Britain.
Sabi pesin tell court say, for im own opinion, e believe say baby Elsa na "full sibling" of di oda two pikin dem.
Dem don adopt di oda two pikin dem and Baby Elsa for now still dey forster care.
Na in January one dogwalker find am for sub-zero temperatures, wey be di coldest night for di year, as dem wrap am inside towel put am for bag.
Na di same area for London dem bin find di oda two pikin dem wey dem call, Harry and Roman.
Dem bin wrap dem for blankets, even put one inside bag.
Family Court documents tok say Baby Elsa bin still get her umbilical cord wen dem find am and according to doctors, na around one hour afta dem born am dem find am.
Tori be say even though she bin dey cold wen dem find her, Elsa bin dey cry and bin dey responsive. Court hear say she dey do well now.
Di Family Court hear say di pikin dem, wey dem don change dia names, go sabi say dem get di same mama and papa wey born dem, and plan dey to make dem contact as dem dey grow.
Di local authority and England Children and Family Court Advisory and Support Service (Cafcass), wey dey advise courts about pikin best interests bin no want make dem report di sibling link.
Di Met Police tok say na di court go decide weda dem go report di link between di children.
But dem tell court say dem no want make e lead to struggling mama dem to abandon unwanted babies for public.
Carol Atkinson wey be di most senior judge for East London Family Court gree say "Abandonment of pikin for dis kontri na very, very unusual event."
She add say if she refuse dem to report on di mata, e go affect "public consciousness" about tins like dis and block open justice for dis kain cases.
BBC and PA Media chook mouth say to report on dis kain mata sef fit help authorities to find di mama and papa wey born dem.
Dem no dey record plenty babies say dem dey abandoned wen dem born dem for England and Wales.
Di ONS only publish data till 2015, wey show say from 2012 till 2015, no babies bin dey registered as abandoned and for 2011 na only one dem log.
But academic researchers say di numbers fit be more, like 16 per year, for analysis wey dem do to cover from 1998 to 2005.
Tori pipo bin report say dem find one abandoned pikin for Hackney, east London for 2020 and anoda one for Birmingham for 2021.
Months later, dem find di mama wey born di two of dem.
Dis na near wia dem find Baby Elsa for January for di junction of Greenway and High Street South in Newham, east London