If you are plugging in a device that does not need Railsync you can use the side port on a UP5 - like t plug in a PR3 or Locobuffer.
You can use the front jacks for that, even.
RR-CirKits has a 1 to 5 spliiter for less than $7.
Not too hard to build one, piece of perf board, and som 6P6C pc mount sockets from a supplier like Mouser.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.