Hello Paula,
You are most unlikely to find any Jewish records in the online LDS databases. The two records you cite are from the parish records of the Protestant church of Rehme, which lies to the west of Hannover.
Do you live anywhere near to an LDS Family Hisotry Library? You could then at least consider ordering some of the records from Wolsztyn that have been filmed. Jewish vital events may have been recorded in the Protestant or Catholic parish records.
The disappointing reality is that the vast majority of the records of the numerous Jewish communities of the province of Posen were destroyed. I am, at least, in touch with an American woman who is also researching her Schiff ancestors from Wollstein/Wolsztyn. She is currently travelling in Germany, but will send me a couple of bits and pieces on her return to Texas. However, none of the names of her family members appear in any of the early generations of your ancesotrs, so it is impossible to judge whether the two families were related.
Justin