Answer:
(Fatwa: 262/242/B=1432)
No, you will not have to observe purdah with the brothers of your phuphi, they became your mahram, as foster uncle is mahram in the same way, the mamu of foster mother is mahram. You need not to observe purdah with them.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
