Gender: girl
There was one Sara Bunimowicz and her birthday is right in the range of 1921-1927. I believe that this is the right one. She was also the only female, all the others were males.
There is no record that I can find of Sara or any other Bunimowicz that were deported. Szmul died in the Ghetto, and was never deported.
I have done hours and hours of research, using many different variations of Sara's name. I can't find anything on her at all. I used the variations you suggested and also Bunim, Bonim, Bunimowitz. I also used the variations of her first name with the variations of the last names. I looked to see if there was any record of her being born IN the Ghetto, or if she got married during that time. I looked for death certificates, and any sign that she died in the Ghetto, but in the Holocaust survivors, she is listed, although she made no testimant, or anything like that. I actually think that she may have changed her name completely. On her page that says she survived, all that is listed is her address in the Ghetto, and her birthday. She literally disappeared, and I have no idea where to look anymore.
In the Postwar database of survivors, Sara's name is listed when you search under Sara Bunimowicz, there is very little information after that though. Also her possible, and most likely her mother Eugenja (Eugenia) is also listed with her. Although when I searched for information on Eugenia I found nothing. I found no liberation date, her birthdate wasn't listed either.