JRI-Poland.org (Jewish Records Indexing - Poland) is a must for anyone researching their Polish Jewish roots. Four of my 16 second great grandparents came from Poland - Samuel Newmark, Rose Cantkert, Morris Blatt, and his wife, Belle.
Not only have they indexed a lot of records, and are slowly digitizing those records and linking to the images from the index, they provide a summary of the records that are available from each town, and the status of the indexing.
As can be seen below, while they aren't done, they've done a great job indexing the available records from Losice, where my Blatt ancestors came from. Unfortunately, my great grandmother, Anna Blatt, was born in 1888, and her older sister, Blanche, in 1886. Neither year is available. I interpret that to mean that the records from those years haven't survived. If so, no amount of waiting will make them magically appear online.
That means I have to rely on the records that do exist.1) Anna's father was Morris (Moshe) Blatt, son of Jacob or Yankiel Blatt. (Source: tombstone)
2) Moshe Blatyta, son of Yankiel Blatyta married Chaia Beila Boksern in 1885. (record indexed, and digitally available online). Chaia Beila was 16 and Moshe Blatya 22. It was the first marriage for both of them. Many other individuals with the Blatyta surname shortened it to Blatt.
3) Anna's daughter, Belle, and Blanche's daughter, Belle, were both named after their grandmother (Family history).
Family history indicated Moshe Blatt's wife was named Belle Wyman. Jokes were made because their daughter, Blanche married a Wyman. While their mother died in Poland, there wasn't enough of a generational gap to yield too much confusion. However, Chaia Beila Boksern could have had a Wyman ancestor in her family tree, which could have been conflated to mean that it was her maiden name.
4) Moshe Blatyta was born in 1862 (Record indexed). According to his death certificate, Morris Blatt was born in 1864. Both 1862 and 1864 birth records have been indexed. That doesn't mean there weren't birth records from 1864 that have been lost.
There could have been two Moshes son of Yankiel born two years apart. But absent contrary evidence, I'm leaning towards accepting that there was only one. I admit that the availability of the birth records for both Moshe and his father, Yankiel Blatyta (though not yet digitized) is an influencing factor. I'm also slightly influenced by the fact that if the relationship is correct, according to the research of another genealogist, my grandmother was second cousins with Jay Black (David Blatt) of Jay and The Americans.