H4 extension


Hi, my scenario is as below. We all got visa stamping in passport until July 2019. But last year when my primary h1b holder filed an amendment for location changa, his i94 and i797 is reduced to may 2018. His company is filled extension for him and for us (i539) under normal process. However primary h1b holder trying to change employer and new employer on to do the premium. But they say h4 extension is not required as we have valid stamping in passport. So, is new i94 and i797 for primary holder will not affect dependent h4 holders? Pls clarify urgently