I want to know that which milk makes muhrim? I mean for example: I am Ahmad. I took milk at childhood from a woman, after that her husband died and she got marry other husband. Now she milked a girl. Now can Ahmed marry this girl? Ahmed took milk when she was with her first husband and that girl whom Ahmed wants to marry she took milk from same woman when she was under other husband. In other side boy and girl took milk when the woman was with different husband.
بسم الله الرحمن الرحيم
In the above mentioned case you cannot marry that girl as both of you have turned foster brother and sister with the relation of suckling. As the nikah of real brother and sister is unlawful, in the same way the nikah of foster brother and sister is unlawful. The holy Prophet Muhammad (صلى الله عليه وسلم) said:
يحرم من الرضاع ما يحرم من النسب.
Allah knows Best!
Darul Uloom Deoband