i am divorced with 3 children,i share custody with the mother,she sees them every sunday for 2 years could she get full custody?

They have lived with me since we split over 2 years ago. She is getting married soon and I think she will try to take me to court for full custody so they can live with her, kids are 9,7,3 years old. I have raised them for the last 2 years she sees them every sunday mostly. We share full custody now but have lived with me since she left. Could she possibly have a good chance of getting custody of them to live with her after 2 years when she gets married?