fauxto Photo date is already used when calculating suggestions, and it helps.
With birth and death dates as strict rule is quite difficult, since photos quite often have wrong dates, expecialy when we are talking about historical pictures scanned from the paper. That would be exactly where we need this feature most, but this is exaclty where it will fail the most.
As to “who with whom” - I have doubts this idea would improve recongition rate by noticeable margin, epecially taking into acount that date is already a factor. But this is just my “gut feeling”, I did not do serious research on that. So we can still keep it as one of the ideas.
