You can assign the face of fabric or seam material to the inside of a garment.
To assign material to the inside of a garment:
Dress the avatar.
In the 3D window, right-click the avatar. A menu is displayed.
Click Hide Avatar.
On the Main toolbar, click Assign. On the Horizontal contextual menu, ensure Pieces is selected
On the Resources tabs, click Materials.
Select the fabric or seam you want to assign.
Go to the 3D window.
Click on the inside part of the garment where you want to assign the fabric or seam.
The face of the selected fabric or seam is assigned to the inside of the garment.