Hi Jenny,
If this helps, my dietician told me to transition from breast milk to neocate quite quickly.
So if he won't drink straight neocate, mix bm with neocate, 75/25.
The next one 50/50.
The next one 25/75.
The next one all neocate.
So they don't get used to the taste of the mixture and you get stuck at one stage.
To be honest, I couldn't get LO to drink neocate from a bottle or sippy cup (mixed or straight) so I had to buy a completely new cup then sat down with her for one feed and gave her neocate. I think I did this for a while then gradually swapped more and more feeds for neocate. Now she loves it and gulps it down.
Good luck!