I just read your post and wanted to say that I think it's *awesome* that you treat these girls like your own.... I know so many women who take on the role of the "evil step-mom" if you will and it's so very sad (not to mention immature). After reading your post is just breaks my heart for the younger girl (I have a 5 year old daughter so I guess it hits close to home) . I could not imagine treating any child like that, especially a biological child. Has anyone (preferably the dad) called out the bio mom on her behavior with examples of how she favors the older one, ie, went to lunch with this daughter on this date, did this for the older daughter on that date, etc.???
I wish I had advice to give. I think in that situation I would probably be inclined to make it a point of recognizing the younger daughter's achievements (as well as the older daughter) and just doing what I could to make her feel special. At any rate, it sounds like they are very lucky to have someone like you in their lives!
-cdg
There is very littlle, if anything, that you can do to change the actual circumstances. You cannot control other people's (in this instance, the biological mother's) behavior. However, you can be empathic with both of the children and be available to hear their concerns. I would let them take the lead in broaching the subject, rather than you bringing it up. It's best for you to keep some distance from it and let the children, if you will, have their respective relationships with their biological mother, for better or worse. An obvious point of concern is the hurt feelings that may be experienced by the younger of the girls. But the older of the two, even though she has the attention of the mother, may feel bothered by it as well and may feel uneasy about what her mother is doing.