أحسن الله إليكم a young (18yr), orphan revert sister still has to live with her adoptive guardians, she is not able to live with any blood relatives. She has been with them since she was a baby, and was raised by them. Is she allowed to treat the man as her father in affection and showing her hair?

Ustadh AbdulAziz al-Haqqan

There is no such a thing in Islam, unless his wife breastfed her 5 times that sufficed her while she was younger than 2 years of age.