Sure, you can add additional agent licenses up to a total of 100 for a BE6000 deployment.
The ordering process is as follows:
Order your preferred starter bundle with your other BE6000 licensing requirement using R-CBE6K-K9 (as you have indicated above).
You then need to order the additional licenses using the standard CCX ordering process. The ordering guide is here, but in summary, you just need to order the required agent licenses using the L-CCX-90-NEW-LIC top level part number. Enhanced agent licenses (L-CCX-90-N-E-LIC) are available under this.
Alternatively, try using the Quick Pricing Tool - this will automatically build a bill of materials for you based on your functional requirements.
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