Tanya Sheahan, 36, found out about her political cousin earlier this year when the First Minister discovered some of his ancestors had set sail for the US in the 1870s.
The transatlantic Salmonds were among the first pioneers of the new state of Minnesota, running land and dealing in cattle, with two of them even becoming famous for their unusual stagecoach driving skills. The genealogical research discovered Miss Sheahan's great-great-great-great-great-great-grandfather was Mr Salmond's great-great-great-great grandfather.
In honour of her links to Scotland's political leader the art teacher will fly to Edinburgh with fiancé Robert Levander, 40, to hold their wedding next year.
Miss Sheahan, from Swartz Creek, Michigan, will stay less than 660 feet from the First Minster's official residence and has asked Mr Salmond to be her surprise VIP guest.
She said: "Both Robert and I have Scottish roots, so when we join our two families we will have quite a Scottish clan in our house.
"It was amazing to learn I was related to Alex Salmond, and it's only fitting as a direct relation of mine in the old homeland that he should celebrate our big day."
A spokesman for Mr Salmond said he has been "fascinated" by hearing of his ancestors' exploits in the US. He added: "The First Minister looks forward to the chance of meeting up with Tanya."