Make one thread per character, convos can happen in threads for either, does not need to be both.
How to name your thread:
Put character names and the device. (O/C)
For example, if Aella was texting Akyrie:
Aella's phone (Akyrie)/b]
Emails Ed/Axel
You can go by dates or by days.
Make sure your convos are time stamped in the thread!
Rengoku Academy
For all the side threads