[German Physicist Max] Born wrote: "[...] I went to Cologne, met Minkowski and heard his celebrated lecture 'Space and Time' delivered on 2 September 1908. [...] He told me later that it came to him as a great shock when Einstein published his paper in which the equivalence of the different local times of observers moving relative to each other was pronounced; for he had reached the same conclusions independently but did not publish them because he wished first to work out the mathematical structure in all its splendor. He never made a priority claim and always gave Einstein his full share in the great discovery."Born also spent 3 years trying to convince Whittaker to credit his friend Einstein for special relativity, but Whittaker wrote that Lorentz and Poincare had it all before Einstein. Aa Born wrote to Einstein:
Whittaker, the old mathematician, who lives here as Professor Emeritus and is a good friend of mine, has written a new edition of his old book History of the Theory of the Ether, of which the second volume has already been published. Among other things it contains a history of the theory of relativity which is peculiar in that Lorentz and Poincaré are credited with its discovery while your papers are treated as less important. ... As a matter of fact I have done everything I could during the last three years to dissuade Whittaker from carrying out his plan, which he had already cherished for a long time and loved to talk about. ...
He insisted that everything of importance had already been said by Poincaré, and that Lorentz quite plainly had the physical interpretation.
I don't see that these self-serving quotes mean much. The fact is that Minkowski gave Einstein very little credit, and Minkowski cheated others out of credit also. Minkowski died soon afterwards, so we do not know what he would have thought of the credit dispute.
Born wrote some papers on the relativity of rigid bodies, as there were such a thing. He seems to have understood the Lorentz-Einstein version of the theory, but it is not clear that he accepted the Poincare-Minkowski version.
As discussed here, Born's opinions on the matter are confusing. While he refuses to give Lorentz full credit for relativity, he implies that he never read Poincare's papers until much later, and when he did, he admitted that Poincare seemed to have the whole theory before Einstein. It appears to me that Born wanted to credit Einstein, but could not find a good reason for doing so.
Born's opinion might be important if he had first-hand knowledge of unpublished opinions. He was good friends with Einstein, Lorentz, and Whittaker. But we don't need Born to tell us what was published in the original papers.