Anybody Remember this story

A young man, the soul survivor of an attack on a wagon train to the west is transformed into a copy of a dying young woman to care for her baby by an alien device. Later found by the woman’s young son and husband. He is persuaded to continue west with them to care for the boy and baby. Gradually falling for her new family.

I had the story saved on a now dead kindle as a document and cannot find it on my laptop.