Michelle, in order for anybody to answer your question, you're going to have to supply a bit more information.But first:
Your grandfather and great-aunt were not born in Romania!Until 1918, Transylvania was part of Hungary.Thus, your grandfather and your great-aunt were born in HUNGARY.In 1919, following World War I and the break-up of the vast Austro-Hungarian Empire by the western Allies, Hungary had to cede Transylvania to Romania.
Pre-1919 Hungary was composed of many nationalities, all of whom were Hungarians by citizenship, but not necessarily by ethnicity.
Your grandfather and your great-aunt were born in the city called in German KRONSTADT, in Hungarian BRASSO, and today in Romanian BRASOV.Back when they were born, Kronstadt (or Brasso) was a city of about 30,000 people, about equally divided ethnicitywise among Germans (or Transylvanian Saxons, as the Germans of Transylvania are known), ethnic Hungarians (or Magyars, as the ethnic Hungarians call themselves), and Romanians.
So the first question you'll have to answer before anybody here will be able to assist you is this:What was your grandfather and great-aunt's ethnicity?Their last name would be a help in determining ethnicity.(When, by the way, did they come to America?)
And the second important question:What was their religious denomination?
With this additonal information, some one of us may be able to direct you to available records.