dilute the milk. give milk in lesser quantity more frequently. the milk powder will not create phlegm but can aggravate the exisiting phlegm and babies tend to have that alot. my son always always has phlegm and i did that. you can google on garlic for babies cough and AGO. it doesn't get ride of the phlegm but it did minimise it though. hope this helps
My baby has phlegm too sometimes. Maybe because i bf him, sometimes i drink cold drinks? Doc say can’t give medicine. My LO will cough and vomit his phlegm and milk on his own and thats how his phlegm clears. If you’re not sure maybe can go and consult a doc?