I just want to point out that nothing in the Immaculate Conception implies an inability to sin. Mary still had free will, and was able to choose to serve God or not; that is why her Fiat is so highly revered in the Latin tradition.
Adam and Eve were immaculately conceived, and they sinned, and we are immaculate at Baptism, and we sin. I don’t know where this idea came up that the IC means Mary couldn’t sin.
I am troubled by the implication, regardless of one’s stance on the Immaculate Conception, that Mary was a sinner prior to the Annunciation. I would really like to see some evidence that Mary was viewed as having sinned in her life prior to the Annunciation, as it conflicts with every tradition I’m personally familiar with.
Perhaps that is not an intended implication, but it’s what I glean from statements like:
Peace and God bless!