You may be thinking of Megillah 14a:
ודבורה אשה נביאה אשת לפידות (שופטים ד:ד) מאי אשת לפידות שהיתה עושה פתילות למקדש
"And Devorah was a prophetess, the wife of Lapidot" (Judges 4:4). What is "the wife of Lapidot"? That she would make wicks for the Temple
You are correct in stating that the Gemara very rarely details the relationships of children at all.
However, here are a few halachos on the topic.
there is a big sugya regarding yichud in these types of situations (a few of the comments touched upon this) see shulchan aruch even haezer siman 15 seifim 11,22,23 with the classic commentators. also see: ...
In answer to your 2nd question, the following is taken from the Weekly Parsha
titled "From the Orchards of Jerusalem" by Daneal Weiner:
When would have been the most appropriate time for Moshe to pray for
entrance to Erets Yisrael? That would have been the last Rosh Hashanah
(R"H) he experienced. Moshe knows that B"Y is going in to E'Y ...