It is very possible, but not directly with OBS. There are two ways:
1. Nginx with rtmp module on a Linux system (this means you are ingesting their stream) and you call pull from that ingest into your layout. This also requires a few changes to your firewall for this to happen, not to mention having the bandwidth to do this.
2. The second way is to use StageTEN which is a web service that can assist you with this as well. Downside is it is not free. I can vouch for this as I still use and I also assisted with this software in it's beta stage.