Austrian citizenship through parent and grandparents

[cdjs77]

This might be a bit long but I want to make sure everything is clear:

My grandparents emigrated from Austria-Hungary to the US in 1909 and had their Austrian citizenship when my father was born in 1917 (they didn't even apply for US citizenship until my father was in his 20's). From what I gather, this would make him an Austrian citizen by birth. I would like to apply for Austrian citizenship papers for myself and my children (currently in their early to mid 20s) based on his citizenship at the time of my birth. However, my father unfortunately passed away in 1999 and, as far as I know, never actually applied for his Austrian passport or registered for his citizenship papers. Would this in any way affect my citizenship? I would assume he was a citizen regardless of whether or not he had filed for the proper paperwork.
Obviously I would have to have the paperwork to prove all of this, but would the absence of his registering his citizenship be a problem for me?

My main motivation is actually for my daughter. She is currently finishing up her studies in Switzerland and is looking to do some graduate work in Vienna and we decided it may just be easier to file for her and my citizenship rather than dealing with visa issues, especially if she wants to continue working there after her studies are complete.

[ban.s]

I am not an expert on this subject matter;

your parent and grand parents may have lost their austran citizenships on acqusition of US citizenships.

http://www.bmeia.gv.at/en/embassy/consu ... nship.html