As Darren mentioned, cascading doesn't always work as advertised. Sometimes order listed in the .LIC file can help alleviate that. I can tell you that the serial number makes no difference at all to the license manager. So your reseller was confused on that fact. And also as Darren mentioned, you can't combine a RevitArch into a Suite contract without cross-grading it. There's probably a work around to get what you want though.
FLEXnet License Admin | MSI Cleanup Utility | .NET Framework Cleanup Tool | IPv6 NLM Fix | adskflex.opt Options File | Combine .LIC Files | Disk Space