Looks like an in-house portmanteau jargon term to me. My 2 cents...
Googled your term and there is an interview with a JFE exec (getting warm!) that uses シンパ流通.
https://www.japanmetal.com/news-to2020070297552.html
Looks to me like a supply chain/channel term so my best guess is `partner distribution` or `alliance distribution` may make sense.

ＪＦＥスチールとの連携を徹底的に強化し、シンパの鋼材流通企業ともしっかりスクラムを組み、未曾有の危機を乗り越えていく。