According to NBC News, Senate Intelligence Committee investigators have asked Michael G. Flynn, son of former national security advisor Michael Flynn, for information related to his work as his father's aide and travel companion at the Flynn Intel Group, the consulting firm the older Flynn started when he left government service:
The younger Flynn, 34, accompanied his father on a 2015 trip to Moscow, where the elder Flynn sat next to Vladimir Putin at a dinner to celebrate Russia’s state-funded media network, RT. The younger Flynn can be seen in video from an associated event.
NBC says Michael G. Flynn has not responded to the requests, and the committee could subpoena him if necessary.
Special Counsel Robert Mueller also is looking into Michael G. Flynn's role with his father's consultancy.
Russia Probe: Senate Asks Mike Flynn’s Son for Documents, Testimony (NBC News)