I am concerned about my sister in law, and my two nephews. Whilst I do think that she does genuinely love my nephews and would do anything to avoid them getting hurt, there is something not quite right about her behaviour in relation to the children's health.
One of my nephews has a genuine (common and manageable) medical condition however having had this diagnosis confirmed by a medical professional and appropriate treatment advised, she has decided to use alternative therapies instead. She also gives these therapies to my other nephew, who does not have any medical conditions diagnosed. Both boys are on a cocktail of 10+ vitamin and mineral supplements and herbal remedies, and the one with a medical condition does not receive the conventional treatment that is known to help his condition in many people. The last few times I have seen him, his condition seems to be getting worse rather than better.
In addition my nephew has tested positive for multiple food allergies, however my sister in law feeds him food containing these allergens frequently, which may also be affecting his medical condition. However she excludes different foods he is not allergic to from both his and his brother's diets, saying they are the cause of his medical condition.
She takes both boys to an alternative medical practitioner on a frequent basis, forcing them to have unpleasant blood tests before feeding them more and more pills and potions. I think she genuinely believes that they are both ill and she is making them better, which is why I don't think this is MSBP. But I don't know what it is. Hypochondria by proxy?