Ok.. unfortunately we do not failback to the primary with data. The primary is left usable and running during the DR test and the standby is opened just for the duration of test then resyncronized with a full backup and new log shipping jobs. that is the policy.
Steps are we drop logshipping, open the standby, and at the end of the test resync the standby and resetup logshipping. I was hoping that if we stopped the jobs on the primary(instead of dropping) that after the test was done I could take a differential backup, resync the standby with this backup and let then let the log shipping jobs run. This is a big database and takes a long time recyncing from a full.. Thanks for getting back!