How do you become a legal guardian if one parent has dementia and one parent is a drug addict?

[Mazzles1]

This is such a complex situation... So my family member has a drug addiction and is neglecting his children. His wife has alcoholic dementia, therefore the eldest sibling (21) wants to become legal guardians of his 2 younger brothers (13 & 14) he had essentially raised them anyway whilst my family member and his wife have been drunk and high. How do we, by law grant the eldest child legal guardianship of the children? Also, please don't suggest that the 2 younger boys go into care, this is the whole reason we want to avoid this, when the most stable figure they've known is their eldest brother. There is no reasoning with the drug addict and I don't know where to turn to help the eldest sibling.

He needs to apply to the courts to be appointed as special guardian to his siblings. There is information about this on the goverment website at Become a special guardian: What is a special guardian - GOV.UK (www.gov.uk)