The trio will take it in turns to play the 12-year-old's only child.
The soap's youngest stars were cast after agents put up posters in maternity wards around the region asking for twins to play the newborn.
The girls father, Martyn Halliwell, said: "My cousin suggested that we should get in touch. He said 'There is a high demand for twins, let alone triplets.'
"We sent some photos over and within two hours we heard back to say they had a client who was interested. On the Monday we were at Coronation Street."
Martyn and the triplets mother Laura Slinger are said to be delighted at how well filming has gone so far.
He added: "One of the triplets cries on cue so when they need a crying baby we take Elsie down for filming and when they need a calm baby we take Erin."
The babies will make their first appearance on Good Friday when a shocked Faye starts having contractions in the flat above Dev’s corner shop.
Faye is accompanied by her only confidante Craig, having kept her entire family in the dark throughout her pregnancy.
Debbie Rush recently said that her on-screen daughter remains in denial for quite a while.
She said: "Faye doesn't choose the name for a while because she's in denial. But Anna, being the type of mother she is, desperately wants Faye to bond with the baby."