Name for compulsive need to mimic another's symptoms of illness?
Siblings as children do this alot. Most people grow out of it. I would think these symptoms reflect a kind of hypochondriasis which is a factitious disorder with an underlying dependant (or inverse dependence) disorder. It could also be an incorrect empathic response due to a narcissistic disorder. The aggressive features as a response to others doubts definitely is a little paranoia and tends me to lean to some kind of narcissistic attention getting type thing. In rare cases it could be a full blown extreme factitious disorder. Faking tests and everything. They had an entire episode of house (s5e18) dedicate to the lady who publically urinated green and faked a seizure to get House interested in her fake illness.