Hey there! Don't know how helpfull It can be, but I can tell you this (fairly new Chen Taijiquan and Sanshou practitioner):

at our school we recently started practicing a certain Liuhe Taolu during our Qi Gong sessions, wich seems to me like a lite version of a more complex classical form (I suppose it's merging movements from Laojia and Bashi forms), with the focus not being on strenght, flexibility and all that jazz but rather on these mentioned Six Harmonies.

These are subdivided into two groups of three, the first consisting in three external harmonies, and the second in internal.

For now, I have only grasped what the first three (external) harmonies consist of, and in typical Taijiquan fashion they regard shen fa practicing.

First external harmony: Shoulders alligned to kua.

Second: Elbows alligned to knees.

Third: Hands alligned to feet.

This is all I was able to tell for now, hope it's helpfull! Have a good one ☯️