DP/PA Coupler and splitconnect

Good day experts,

Please help me in my design.

I have 5 Profibus PA Devices (level monitoring device - non siemens)

1. When do i use split  connect system and what are the application of this? is this comparable with active field distributor/splitter

2. when should i use AFD and AFS?

3. is it always necessary to use AFD/AFS with DP/PA coupler?

4. any comment/suggestion on diagram attach