The good news is that Time Machine will automatically create separate backup files for each Mac on the Time Capsule disk. Each Mac will only be able to see the backups that it has made on the Time Capsule.
The practical limit for the number of Macs that back up to a single Time Capsule is probably about 4 or 5.
So, there is no need to partition the Time Capsule.
That is a good thing......since the TC cannot be partitioned........unless.......you physically pull the hard drive out of the case (which voids the warranty), place it in a caddy or special enclosure and connect that directly to a Mac to perform the partition operation. Then, you have to reinstall the hard drive back in the Time Capsule and hope that things will work.