H4 visa stamping(spouse h1b transfer case)

Hi All, I am having H1b stamped with company A but I didn’t travel to US with them. Later I accepted company B offer and approved i797b. As I am already having h1b visa stamped for company A so I am assuming I don’t need new stamping for company B as visa validilty is there. Are there any chances that they can send me back from POE? Also my wife is going for h4 stamping with my old visa and new petition. Are there any chances of rejection?