You could always have multiple SMS participants in the same conversation talking to each other. However, each participant was previously bound to a single proxy address number through which they received all of the messages in the Conversation. In this scenario, each participant had no way of knowing how many people the proxy number represented.
It is now possible to add your US or Canada based clients as Group participants, utilising a Group MMS protocol. As a result, your clients will observe an iMessage style experience and easily see who said what. This is especially valuable for use-cases which expect an active participation of all interested parties, like wealth management, personal shopping, or real-estate industry.
Explore the Group Texting documentation and give it a try!