Feature Request - Threads inside Threads (Sub-Threads)

Please allow us to make a thread inside of a thread. This could be helpful in some cases, such as discussions where you want to continue on a specific topic. (Ex. You're having a conversation about a new phone that got released. Then you want to talk about the processor, but you don't want to stop the whole conversation and turn it into a processor conversation. In this case, the sub-thread feature would be awesome, because you can start talking in there about the processor, and other people that are interested could also join.) I wouldn't add a split layout for the sub-thread, since that could be confusing. And maybe a maximum on the number of sub-threads you can make.