Questions about citizenship (my father was born in Poland during the second world war)

Hello everyone, I have a few questions about my chances of possibly obtaining citizenship through my late father. I've read through many of the threads on this forum, and it looks like there are some regulars that are pretty knowledgeable about this topic, so hopefully I can get some advice on next steps.

My late father was born in February 1943 in Radycz, Turka, Poland. As I'm sure most of you already know, before WWII, this area was a part of the Second Polish Republic, but at that moment in time, it was part of The General Government controlled by the Nazis. Today, it's Western Ukraine. His father was born in the same town in 1899, while his mother was born in Chernihiv, Ukraine in 1909. After spending some time in DP camps after the war, they finally traveled to America in late 1949, was given Alien numbers, and settled in the Midwest. He ultimately passed away in 1995.

I have records from the International Tracing Service that show their movement around the DP camp system (all of which state he was born in Poland), as well as records (visa applications, Alien registration forms, etc.) from the US gov't for my father and his parents that say the same thing. Based on these records, it appears he was renewing his alien registration well into the 1970's. Unfortunately, I don't have any records from Poland - we've attempted to track any records down using a genealogist based out of L'viv, but unfortunately we weren't able to really find anything.

Here are my questions - first, what's the next best step forward? Obviously any records from Poland would be incredibly helpful, but what's the best way to track those down? Would a genealogist based in Poland (Krakow, etc.) be better? What are my chances of this being successful? Even if we're able to find such records, and based on my father's background, what are my chances of gaining citizenship? What issues/hurdles that I have not mentioned should I be aware of?

Thank you again for reading this long post, and for all of your input.

The problem is that he may never have had Polish citizenship. So, you need to look at the grandparents - you need to find something that proves that they were Polish citizens. The Act of 1920 clearly defines who was given Polish citizenship then - so check there and see if you have any proof that would meet the criteria there. Then, because they were from the territory now in the Ukrainian SSR in 1951, you need to ascertain as to whether they ended up with citizenship of the Ukrainian SSR/Soviet Union on the basis of international agreements.

It won't be easy to prove.

Having said that, you'll get permanent residency in Poland easily if you apply for it. If you want to move to Poland, the process will be pretty painless.

@delphiandomine - Thank you for the response. I'm guessing birth certificates, marriage certificates, and other metrical records would probably be best for this. Where would be the best place to find these kinds of records? Are there professionals out there that can help track these records down? Also, how can one ascertain whether they would've ended up with Ukrainian citizenship or retained Polish citizenship?

@Mike98989
Your great grandfather was born in 1899 so he obtained citizenship in 1920, his son would be Polish at birth assuming the parents were legally married, because children of unmarried parents at the time took their moms citizenship.

If your grandparents stayed in the USSR into the 50's then they probably lost their citizenship due to bilateral agreement between Russia and Poland.

Its best to hire a local company to do a doc search, there are multiple archives and it will be difficult to navigate them without writing Polish, Ukrainian, you can contact me at thesipguy at Gmail dot com for a quote.