refuse to drink milk

hi mommys... i ada twins now dah 9months.. sorg dia minum susu + mkn （selera ）.. but sorg lg refuse minum susu.. skli minum 2-3 oz ja..berat dia still ok tp makin susut.. any suggestions how nk bg dia lalu minum susu ？beza berat dr stgh kilo skrg dh 2kilo ?