Complex sentence: In an attempt to make progress, herr Flick has decided they shall both attend the activity in the church the following Saturday; they do not know that René is the groom or even that there is a wedding to be held.
Split into simpler sentences: In an attempt to make progress, herr Flick has decided they shall both attend the activity in the church the following Saturday. However, they do not know that René is the groom or even that there is a wedding to be held.