Use these options to set what happens when you select .
When this option is off, Move and Sew UVs only moves and sews the selected edges.
When this option is on, Move and Sew UVs automatically moves and sews together any selected shells below the size set in Number of Faces.
When Limit shell size is on, this setting specifies the maximum number of faces in each shell. Larger numbers result in fewer shells.
After performing a Move and Sew operation, you can select the history node (polyMapSewMove) in the Channel Box and adjust the Number of Faces until you achieve the results you want.