Q. Re- questions 935 – 938. How can you have a conversion on an already married to each other couple and then do the wedding the same day, do you not require 3 months of separation to establish if a child was conceived from Jewish parents bekdusha or not?
How about having the seven days of separation for “Dam Chimud” required when a choson proposes marriage?

A. The Talmud (Yebamos: 42a) requires indeed a three month separation for a couple when they convert in order to separate between the offspring conceived in kedusha or not, and so rules Rambam (H. Geirushin 11: 21.)
However, Dagul Mervava (Y.D. 269: 9) permits when the already married couple are aged and she cannot anymore conceive. Igrois Moshe (E. H. 2: 4) expresses further leniency if the geyores is menstruating, since today it is a common sign of not being pregnant. He does not require the three month separation if that involves the hardship of leaving home. On the contrary, he recommends accelerating the conversion so not to delay mitzvois.
Horav Shlomo Miller’s Shlit’a opinion is similar when in need,but recommends this days to take an easy and available pregnancy test. The seven day separation due to “dam chimud” (A discharge caused by the excitement of the impending new marriage making the woman a Nidah,)is also unnecessary since they are living already together.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a