When we went in January, DD was 2.5 and had just done BBB and was dressed in her Cinderella dress. When the sisters came out from the CM area, they saw her and said, "Hi, CinderSOOT!" and walked right by her.
DD had gotten used to running up and hugging the characters when it was her turn in line, and DH and I wanted to see what they would do. So, when it was her turn, we said, "Go ahead" and there she went, this cute little 2.5 year old running at them with her arms outstretched for a hug. Drizella just looked down at her and didn't respond, so DD turned to Lady Tremaine, who of course did nothing, so then poor DD turned to Anastasia who said, "Awwww..." and stooped down to give her a hug. Then she said something like, "how could I NOT?" Drizella ended up hugging her, too, but LT would not budge. We wanted her to break SO badly, so DH told DD, "Go ahead if you want... Lady Tremaine looks like she could use a hug," to which she held out her hand and said, "ALL set!"
If our adorable two year old couldn't get her to break character, I doubt anyone can!!