Technical Application Question

[ctn8]

If I plan on sending additional letters of recommendation to schools after the original application has been sent, do I still need to assign the letters to the school during the original application process? For example, I assigned "L2" to my American University Law Application. I also want "L1" to go to American as well. However, since "L1" has not been processed by LSAC yet, I did not assign it. So can I still send "L1" to the school even if I didn't assign that letter during the application process? In other words, do all letters that I want to send have to be assigned to that school (even if I'm still waiting on the letters)? Any help would be much appreciated.