Would anything of significance have changed if in the regin of the Old King there was a wedding between a Targaryen and Martell

So really, everything stays the same as we know it. Viserys succeeds Jaehaerys, and the Dance still happens. The only change is that one of Jaehaerys’s younger sons or daughters survives and marries a Martell. Would this really have changed anything? Would the houses be on slightly better terms, or would it do nothing whatsoever.