Entertainment Weekly has some information about the sisters and Andrew.

I can almost see the light at the end of the tunnel! Ringer‘s hiatus is nearly over. Share bit of scoop to get us through?  – Amelia J
Get ready for a big reveal about Bridget/Shiv past! Creator Eric Charmelo told a group of reporters at a CW screening in LA that exactly what put Siobhan on the path of revenge and Bridget on the path to redemption will soon come to light. “There’s one singular incident that drove this gigantic wedge between the sisters, and we’re going to discover what that is,” Charmelo said.

I would LOVE some Andrew-related Ringer scoop. (Ioan Gruffudd = swooon) — Felicia
Remember appearances can be deceiving — so warns Charmelo. “Everybody has secrets and lies, and what you see at face value is hardly the person who they are at their core,” he says. “Andrew has a deep, dark past just like most of the characters of the show.”