Feeding breastmilk purchased from store

Since foster relations are treated as blood relations in marital matters and buying breastmilk from a store to feed your infant doesn't tell you who the foster mother is, is it regarded as forbidden? It is allowed to nurse your child by paying someone in Islam > ...And if you wish to have your children nursed by a substitute, there > is no blame upon you as long as you give payment according to what is > acceptable... **(Surah Al Baqarah:233)** Although in this way one cannot guarantee to know the foster brothers/sisters(because she may also feed some other child in return for payment), Allah has made it halal. So, the question is not very different from this scenario except the foster mother is not known. What do scholars say on this matter?