Purification is listed in Leviticus for all the things that people do and need to go make a sacrifice...bleeding, giving childbirth (which has blood), touching someone who is unclean because they're bleeding, etc... The "their" could refer to just Mary and Jesus, or it could refer to Mary and Joseph and Jesus. The text doesn't say, and it really doesn't matter, does it? They abided by what the law told them to do.
Yes, and (Lev. 12:1-8) lists the purification process for a woman giving birth. Nothing said about the husband or child needing purifying.
(Lev. 12:1) "...If a woman have conceived seed, and born a man child: then she shall be unclean seven days...."
(Lev. (12:8) "...if she be not able to bring a lamb, then she shall bring two turtles, or two young pigeons....and the priest shall make an atonement for her, and she shall be clean.
Well, these things are important to me. Mainly because my KJV says 'her' and not 'their', indicating only Mary is involved.
And note (Luke 2:24) where it was two pigeons that were brought, indicating only Mary is involved.
Lees