The parts of semi-simultaneous compounds partially overlap temporally. The magnitude of phonological reduction [Phonology - 3.1.1] and thus, the recognizability of the stems vary from one compound to the other. Certain compounds have recognizable elements, whereas others do not.
An example of a semi-simultaneous compound involving movement reduction and handshape assimilation is the compound man^tall (‘elder brother’). man is signed with a 2-Handshape proximal to the chin making repeated contact; tall involves a :-Handshape making an upward movement on the ipsilateral space.
In the compound, the 2-Handshape moves from the chin to the upper ipsilateral area without repetition. That is, we observe (i) loss of movement in the first part, (ii) loss of handshape in the second part (which is a progressive handshape assimilation). See the examples below:
man^tall
‘elder brother’
say^bad
‘to swear’
eight^zero
‘eighty’