Philemon: 2nd Person Singular or Plural?

In standard English, we do not make much distinction between singular and the plural in our second person pronoun references. "You" ambiguously refers to either one person or to many.  [Of course, an exception to this rule must be made for those people who prefer to use "you's guys," "you'uns," or "y'all" to clearly indicate plural.]

Unlike standard English, Greek indicates singular and plural pronouns. One such significant example?  Philemon 1:23-25

"Epaphras, my fellow prisoner in Christ Jesus, sends greetings to you [singular], and so do Mark, Aristarchus, Dems, and Luke, my fellow workers.  The grace of the Lord Jesus Christ be with your [plural] spirit." (ESV)

English does not make it clear, but the first 'you' seems to refer just to Philemon (1:1) and the second to the larger church audience, which would also likely include Philemon (1:2).