Still not what I'm looking for but an excellent overview on sibling/young relative abuse and empathy. Read carefully, I see many implications in this current case we're dealing with:
http://www.psychpage.com/family/library/sib_abuse2.htm
"De Jong (1988) and Daie et al (1989) present several factors in families that can lead to sibling or cousin abuse. Abuse can arise in an environment that:
....fails to protect the child, though poor supervision/monitoring and poor choices regarding babysitters and surrogate caretakers; examples include allowing children to remain in the care of known siblings abusers, or a general lack of supervision of the children and knowledge about their activities in and out of the home
....is based on a multi-familial home were older children have caretaking responsibility for younger children; combined with poor boundaries, this situation can allow older children to pressure younger children into meeting their sexual interests and needs..."
more at link
http://www.psychpage.com/family/library/sib_abuse2.htm
"De Jong (1988) and Daie et al (1989) present several factors in families that can lead to sibling or cousin abuse. Abuse can arise in an environment that:
....fails to protect the child, though poor supervision/monitoring and poor choices regarding babysitters and surrogate caretakers; examples include allowing children to remain in the care of known siblings abusers, or a general lack of supervision of the children and knowledge about their activities in and out of the home
....is based on a multi-familial home were older children have caretaking responsibility for younger children; combined with poor boundaries, this situation can allow older children to pressure younger children into meeting their sexual interests and needs..."
more at link