1. Direct (not hearsay) witness Ruth Ndesandjo afirms birth dates of her two boys exactly matching their relative ages in both the family and studo pictures which Mark Obama Ndesand says ar of himself and his brother.
2. Direct witness (not hearsay) Mark affirms the existence of his brother and that it is he and his brother David who are in the picture together at the salon and in the family picture.
3. Malik (hearsay witness to the picture) posted a picture of David on his US charity website, but Malik also affirms the existence of David.
That is solid multiple first person witness affirmation acceptable to any honest investigator or historian absent any credible evidence to the contrary of which there is NONE to my knowledge.
Your problem is that you are assuming that these people are all telling the truth and have not been paid money to lie, or threatened to get them to lie, or are lying in order for financial gain.