Query for knowledgeable Latin speakers

[beatitude]

I have commissioned AuthorOfMyLife (who is a talented embroiderer) to make a green scapular for a friend who is very ill. I want to tweak the traditional prayer ("Immaculate Heart of Mary, pray for us now and at the hour of our death") so it contains my friend's name ("Immaculate heart of Mary, pray for Sammi now and at the hour of her death"). And I want it embroidered in Latin. I am going all out here.

That is not an abbreviated form of Samantha. It is her actual name. I am not sure if I can have 'ora pro Sammi' in Latin, as most names would take the accusative form. But which declension would Sammi fall under? 'Sammiam' doesn't sound right. Could I treat it as one of those rare names that can't be declined and just have Sammi?

Edited August 8, 2015 by beatitude

[Luigi]

Sammi is not a traditional Latin name. Treat it as a "borrowing" and just import it wholesale into the Latin. 

Orif it makes you feel better, put Sammi in quotation marks so it stands as separate from the Latin. 

[reminiscere]

Cor Immaculatum Mariae, ora pro Sammi, nunc et in hora mortis suae.

Please be assured of my own prayers for Sammi, through the intercession of the Immaculate Heart of Mary.