So far, I've run into minimal problems with cleaning up a few duplicates for my paternal grandmother and her parents. So I want to finish his ancestry by taking on her grandparents (I don't have any research myself that goes any farther back than that).
Rachel's paternal grandparents are Mendel Weinglass and Frumat "Fanny" Zorkel, and her maternal grandparents are Anschel Grodowitz and Hannah "Annie" Siegel. All 4 appear in the FamilySearch Family Tree here:
Mendel Weinglass: https://www.familysearch.org/tree/person/details/9ZMC-NBJ
Frumat "Fanny" Zorkel: https://www.familysearch.org/tree/person/details/9ZMC-NBV
Anschel Grodowitz: https://www.familysearch.org/tree/person/details/L6KM-14C
Hannah "Annie" Siegel: https://www.familysearch.org/tree/person/details/L6KM-1HH
I was not previously following Anschel and Hannah, so I fixed that, and I fixed Hannah's surname.
And that appears to be it. No duplicates here. That means I'm finished with checking on my paternal grandmother's ancestry (although there are still fixes to be done to her siblings and others).
Next up tomorrow: I begin to tackle my Irish ancestors (the Smiths, Bannons, Reillys, and Hylands). This should prove much more complex, and I suspect, educational.