Thread:Help talk:Adding subobjects using Semantic Forms/Adding properties to form values.../reply

Yes, you need two templates, one for the page and one for the subobjects since there are supposed to be several different items in the box. So you will need to use the multi instance form.

Do not add #set in the item template since you are already passing the respective values to the subobject. I prefer setting all values into the subobject via the form, e.g. by additionally adding  but that's probably a matter of habit. Thus I believe it is easier to grasp which values are actually annotated via the subobject.