see reference in this post), it can be observed that there is actually very little reaction to the surface of the tea, whilst the fluid sims I've got have a very visible reaction.
Hence, I've decided to go with a procedurally based solution in SOPs - to actually model and procedurally animate the milk stream as geometry. Looking at the stream, it can be generated using multiple curves that are shaped and joined together. A handy way of generating a mesh from curves, is with volumes - or more accurately, signed distance fields. A good readup can be found in "Levelsets In Production: Spider Man 3".
I did a quick test to make sure the blending works in Houdini, just using a Volume Mix set to minimum.
A few nodes are added to ensure that both sdfs to be merged are of the same dimensions.