תרגום - אנגלית-לטינית - dear loving sister

Sister should be:

sŏrŏr, sororis
III decl, f

Can i know where did you find "germana"?

Personaly, I found that here : http://www.prima-elementa.fr/Dico.htm

germana, ae, f. : sœur germaine.

problem is that I don't even know what "sœur germaine" means in French, I thought this was only used with cousins!

in italian "sorella germana" is
"Persona di sesso femminile nata dallo stesso padre e dalla stessa madre (sorella germana)"

"someone, female sex, born by the same father and the same mather"

soror is more general. Even by different father, or different mother [but even with same parents too!!!!]
In Latin "soror" was the most common word (used quite in all the occasion)