on to (?.)

• alive to
• appreciative of
• apprised of
• awake to
• aware of
• behind the curtain
• behind the scenes
• cognizant of
• conscious of
• hep to
• in the know
• in the secret
• informed of
• let into
• mindful of
• no stranger to
• privy to
• seized of
• sensible of
• sensible to
• streetwise
• undeceived
• wise to