“If it were demonstrated to you that you had free will, would you accept it?”
If you wish to do this, to keep it from being merely arguing by assertion, you must first define “what it is, what its parts are, what is contrary to it, connected with it, and like unto it,” as Luther asked of Erasmus. So that we, at least, know what it is you are actually arguing for, and whether what you argue for can exist even in your own universe. I’ll warn you now, not even Erasmus could give a definition that made any sense.
But as to “would you accept it?” That’s like saying, “would you accept that the moon is made of cheese if it could be proved so?” Well, I won’t say I won’t engage with you, but I can’t say I’ll ever be able to believe something I know is wrong.
Whether or not it is demonstrable is not the point. It is whether you would accept it or not if it were demonstrated to you.
Assuming it is possible, if it were demonstrated to you that you had free will, would you accept it?