Yes, I had brought 2 bottles of BB congee & rice when I go to SG and back to HK.
As I took 2 kids, they both passed security & did not ask me anything.
For scissors, I not handcarry.
For water, you may take maximum 150ml water inside bottle for children.
For adult, it's better not bring any water, because security always ask to take out.
But, you may buy after security. It's cheap also, Watson water cost HK$4 for small bottle.
You may request water for milk when get in the plane.