From the diary of Megan:

When the bags that my aunt and I had,were removed from the trunk and taken into the house,the surprise I had been waiting for was upon me. My brother and sister were downstairs,and true to what I believed,the years had changed the two of them,in ways that I could both guess,and didn't expect. My sister and brother noticed the same thing in me,Molly and I favored our mother,just as Scott had a strong resemblance to our father. At first,Molly hesitated to come anywhere near me,until I proved my identity by opening my arms,as if I intended to give her a hug,as I'd done many time before,in the past.

Scott did not need any proof of who I was,a thing which was due to how much older than Molly he was. When all was said and done on that front,I was reminded that they didn't know who the person that had come with me was,so,rather than have her remain a complete stranger,I introduced all three,brother,sister,and governess to my aunt.