The relationship between Rebecca Sewell and Sutton Mercer is unknown.
They have a plan to get Rebecca back with Ted and Emma and Sutton to live together with them as a family.
They also have a plan to get revenge on everyone who did them wrong.
Rebecca gave birth to Sutton and Emma. She gave them both up to a baby broker, who paid Ruth Peterson to sign their birth certificates and had them separated. At some point Rebecca and Sutton meet again, and begin to plot revenge on the Mercer family.
At the end of Unholy Matrimony Sutton is revealed to be working with Rebecca knowing she's her birth mom and they have something planned. It's possible Sutton's known about Rebecca since her return from her disappearance.
It's discovered that when Sutton accidentally crashed her car into the lake, Annie Hobbs pulled her out and took her to a motel but Rebecca was in the motel as well. Rebecca and Sutton are working together in a plot to get there family back together. Rebecca tries to frame Alec for Dereks murder so she can get closer to Ted who is the twins real father. Later on in the season Sutton comes to her senses, stops working with Rebecca and starts to get closer to Emma. Sutton is responsible for the raid on Rebecca's house when she turns in her necklace to Dan and Ethan at their home. Dan later thanks Sutton for helping in the process of arresting Rebecca, even if the cops never find Rebecca.
Sutton: (To Rebecca) "Hi mom."
Rebecca: (To Sutton) "It's all working perfectly Sutton, just as we planned."
- Sutton: (To Rebecca) "I must say that was quite impressive."
- Rebecca: (To Sutton) "How'd it go with you?"
- Sutton: (To Rebecca) "I played nice. Just like you suggested. She still thinks we're hot on the trail to finding our birth mother."
- Rebecca: (To Sutton) "Not going to happen! Alec is gonna spend tonight in jail and many more nights. In the mean time Sutton, I need you to get close to your sister."
- Sutton: (To Rebecca) "Even if I really dont feel it?"
- Rebecca: (To Sutton) "Just do what I do with Alec."
- Sutton: (To Rebecca) "Pretend you love him until he gets thrown in the gas chamber?"
- Rebecca: (To Sutton) "Actually it's lethal injection now. Wish me luck?"
- Rebecca: (To Sutton) "Soon Alec will be convicted. I'll fleece him in the divorce, and we'll win back Ted and have my family back together again. Ted and me, my two twin daughters, the family that should of been.
- Sutton: "Mmhmm."
- Rebecca: "Do I sense reservation?"
- Sutton: "It'd just be neater... If I were an only child. In case you forgotten, Emma stole my life and... Well the girl still has it!
- Rebecca: "And you know why."
- Sutton: "If Ted found out that you've known that I'm your daughter and that there are twins. We wouldn't have a chance."
- Rebecca: "Which is why you need to be nicer to your sister. I can tell she and Laurel... Are determined to get Ted and Kristin back together."
- Sutton: "Yeah. Time heals all wounds... Except yours of course."
- Rebecca: "I need you to get back in there and find out what they're planning."
- Sutton: "So you can foil it?"
- Rebecca: "So we can foil it. Foil... Such a nice... Ring to it."
- How Sutton and Rebecca know of each other is unknown.
- What they have planned will be explored.
- After Sutton's crash Rebecca was at the motel, thats how they know eachother.