I have had to replicate the outside of the trousers on the lining of my trousers. This includes doing my darts and pleats. The difference between my trouser and the lining is that the lining will be cut off around 10cm below the knee. The reason I do this below not above the knee is that it prevents the knee from wearing as quickly and supports the fabric. Because the inside of the trouser lining will be accessible, I will need to overlock the edges of the trousers.
Lining is not traditionally overlocked as it just adds bulk to the inside of the garment and also the inside would not be seen so it isn’t required that it looks pretty.