white_lady
For SG airport, I brought 4 milk bottles, one flask and one water bottle, all filled up with water. I have a separate bag for these bottles alone. So far no problem. The customs officer even told her colleague who was looking at the xray screen, its milk bottles for baby. No question asked.
For BKK airport, I only brought the hot flask half filled, one milk bottle and one water bottle. It's only 2 hours flight plus waiting time, my boy won't drink two feeds of milk. Some more we had lunch in the airport and we fed him snacks as well. So one milk bottle for him was sufficient. It's up to you, I'm sure even if you bring in two bottles, there won't be any issue.