Hiya,
You should indeed use the R-UCL-UCM-LIC-K9 code again for the add-on users. Below BoM for 10 addtional users based on UCL enhanced.
1 R-UCL-UCM-LIC-K9 1
Top Level SKU For 9.x/10.x User License - eDelivery
2 LIC-CUCM-9X-ENH-A 10
UC Manager-9.x Enhanced Single User-Under 1K
3 CON-ESW-LICCENHA 10
ESSENTIAL SW UC Manager-9.x Enhanced Single User-Unde
4 UCSS-U-UCM-A-3-1 10
UC Manager UCSS - 1 ENH User 3 Year Sub Tier A
5 CUCM-VERS-9.X 1
CUCM Software Version 9.X
6 PC-10X-STANDARD-K9 1
Prime Collaboration Standard 10.x
7 LIC-CUCM-9X-ENH 10
UC Manager Enhanced 9.x License
8 UCM-PAK 1
UCM 9X PAK
9 CON-ESW-RUCLUCK9 1
ESSENTIAL SW Top Level SKU For 9.