Marriage with brother's foster sister

It is stated that the foster relations are treated like blood relations in the following hadith. > Narated By Amra bint 'Abdur-Rahman : That 'Aisha the wife of the > Prophet told her uncle that once, while the Prophet was in her house, > she heard a man asking Hafsa's permission to enter her house. 'Aisha > said, "I said, 'O Allah's Apostle! I think the man is Hafsa's foster > uncle.' " 'Aisha added, "O Allah's Apostle! There is a man asking the > permission to enter your house." Allah's Apostle replied, "I think the > man is Hafsa's foster uncle." 'Aisha said, "If so-and-so were living > (i.e. her foster uncle) would he be allowed to visit me?" Allah's > Apostle said, "Yes, he would, as the foster relations are treated like > blood relations (in marital affairs)." - Sahih Bukhari . Is it permitted for a man to marry the foster sister of his brother? Since, that woman is only his brother's foster sister, not for him. ie, What about marriage with blood relation's foster relation?