Name for compulsive need to mimic another's symptoms of illness? I'm trying to research a particular issue that arises as a side effect of anxiety and depression. I'm finding it tricky to get information, mostly because I'm not sure what it's technically called (if it has a term, or if it is documented at all).

The subject has a compulsive need to appear to be experiencing the same symptoms of illness of an important loved one, in particular symptoms that are difficult to disprove (e.g. pain, soreness). For example if the subject's partner has a cold and complains of a sore throat, the subject will immediately claim to also have a sore throat. The subject will also have a compulsive need to take the same medication or treatments as the loved one. The subject will claim all of this fiercely, and will take great to offence to mistrust.

It seems strikes a similar chord with Münchausen syndrome, but the subject does not specifically want care from medical professionals and it only occurs to mirror a key loved one's symptoms. I'm not entirely sure if it is issue of attention seeking, due to attention being cast on their loved one instead; or if it's fear of severe illness and death of another, and by both being ill makes it easier to cope somehow?

The overall cause is not especially relevant, and probably impossible to reckon without further counselling. But the overall compulsion to mimic symptoms of illness - is this a documented disorder? This is a fact finding mission, so any information would be greatly appreciated.
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.