You can create either one backup to tape job for each backup to disk job or include all backup to disk jobs it one backup to tape job - it’s up to you.
During backup to tape job you need to choose existing/create new media pool with attached tape media. Here, again, you can create separate media pools for each job or use one media pool for all backup to tape jobs. In last case, please use "Create new media set on every backup session" media pool option - this will ensure that each backup to disk job will use its own portion of tapes taken from one media pool.
For the detailed option explanation please refer to the backup to tape section (p 424) of the Veeam B&R v7 user guide