In this video (subtitles in English available) at mark 1:28:38 Professor Bezeera comments:
"We also found out that Lucia was left handed, why do we know this? There is an image of her from 1946 when she goes to the Well of the Apparitions to drink water, and there she uses her left hand."
There is another video of Professor Bezeera's, where he talks about a video of the imposter at the same well, and she uses her right hand to drink. If I can find it, I will post it.
In this video the real Sr. Lucia drinks with her left hand (mark 1:23)
In this video the imposter visits the well (12:42)
And at mark 12:56 she drinks with her right hand