Okay. I don't know if you are referring to this happening during "entry" or if you are expecting this to happen in a "batch" (Gendata) rule. I'm not sure I can answer from the batch angle without some thought. However, if you are talking about user Entry "propagating" a MLT from one form to the next, it might be possible with some caveats.
1. The MLT field must have the same name. (Just like normal fields that propagate between forms)
2. The destination MLT fields must be on separate forms from where you are starting. This does not mean that the forms can't have the same name, but they must be separate copies of the form.
3. On the section where you define the MLT field, set the field scope to Global and then skip down to the Edit properties area. In the Post Edit area choose the Procedure named TerPropagate. This will set the module name to Tersw32 (as you need).
If you do these things, then when you complete editing the field on the first form and Tab off, the content should be duplicated onto the other copies of the form.
Note, the reason the MLTs must be on separate forms is simple. Usually, any MLTs of the same name found within the same form may be considered part of the same text. So it only works when you set the scope to global and when the MLTs occur on separate forms.