Dear, When you want to insert additional sub card in live NE40E-X8 router, you can use below steps as per my experience:

1. check device current status & configuration.

2. Shift all traffic to Standby device (if necessary).

3. Shutdown LPU.

4. Insert the new sub card into that LPU.

5. wait for sub card registration.

6. after registration, unshut the LPU & subcard.

*** you can also use hot swap mechanism for this.. this is an additional solution...

very nice & useful information..

really helpful for me..

i really used to with this process