I hear parts of Tammi and Valerie in most of the songs on "Easy". The songs where it sounds like someone is really trying could be Tammi whereas the more confident sounding vocals could've very well had been Valerie's. That said, Marvin and Valerie, as I think about it, weren't wrong in their stories. Tammi was there but not there, ya dig? But, like "[[ain't nobody come to see you)" Otis said, "Tammi was a fighter" so she probably did her hardest to sing on those tracks. Who knows? Marvin, Tammi & Nickolas are not around to explain further [[and even when Nick was alive, Val only talked about it, he remained tight-lipped lol).