If you are my brother, as you say you are, why do you not give some proof?
That should be easy.

There must be some people who can identify you, or some means of satisfying us all about your claim to be the elder son.

I should not resist you, if it were so.

Only my guardians would require clear proof before recognising you.

As to whether I think well or ill of you, that has nothing to do with the matter if you are really and truly my elder brother.