
In order for a victim to be added to the Yad Vashem database, someone needs to fill out a testimony page either online or via physical forms (see under Digital Collections> Shoah name database).
Anyone that is up for it can fill out a witness form after making sure there are no duplicates. The finding duplicates part is a tedious task which requires a lot of attention to detail.
Regarding responses from Yad Vashem. After they launched their initiative to group duplicate testimonies on identical persons I filled out their requested grouping form on multiple family members that had such duplicate testimonies.
Yad Vashem was slow to respond (on the order of several months) but they did group the family members as per my requests.
There is however a real danger of combining two different victims with somewhat similar data into a single person and I saw that happening in our family.
Also, the opposite is true as well. Since testimonies are based on recollections, various people may have put down differing data (year / location of birth, death date/ location or even family members' info) while describing the same victim. In fact I've seen even testimonies given by the same person several years apart on the same family members that had significant differences... One needs to tread very carefully with grouping as this can easily lead to mistakes.
Regarding corrections, they only allow obvious TRANSCRIPTION corrections on prior witnesses' testimonies, they don't allow of course changes in the info itself or the addition of info that doesn't exist on that witness testimony.
I have found the Yad Vashem database and testimonies to be invaluable when they contain recollections that are not (or were not) contained in published records. As was mentioned earlier, it hasn't been possible to correct errors at Yad Vashem directly, I did file one page of testimony for a relative solely to correct an error in one that was previously filed.
My view is that Yad Vashem complements the work done at geni for Holocaust victims. I don't think we need to submit testimonies there solely to harmonize the two projects.
Kind regards - Eric