Caitlin Custer tweeted this on 23 March:   "Currently relaxing and watching TV between takes on the set of Ringer with Juliet’s ‘boytoy.’ Fun first day of work!" This must be the boytoy but as yet we have no idea who is playing that character.
Blink and you’ll miss it, but the three minute RINGER trailer does include a shot of Caitlin Custer and her boytoy. Here it is:

Juliet Martin (Caitlin Custer) apparently caught in the act in RINGER pilot

And here is a photo of Siobhan (Juliet’s mom) and what might be a young Juliet or perhaps one of Henry (Kristoffer Polaha) and Gemma’s twins.

Photo of Siobhan Martin (Sarah Michelle Gellar) and possibly one of Henry and Gemma's children