Though this thread is quite old it is yet un-answered, so I give my comment...maybe helpful for other users struggling over it:
I had the same issue, which lead me to the comment posted on Matts page for SV-SMVI:
http://communities.netapp.com/docs/DOC-1868
Although I got not an answer from Matt himself, the next comment was:
"As far as I'm aware, that's still not an option, but Matt said he would work on adding that functionality. Currently, all valid relationships for the source datastore are updated every time sv-smvi is run."
So either you have just one retention, means one snapvault snap sched, or you have to write your own scripts as described in the SMVI BestPractice Guide TR-3737.
With the use of the SDK you can control which schedule should apply.
If the use of rsh is not a problem (security!), you can even more simplify the process by just issue in the script
rsh filer snapvault update -s smvi_<backupname>__recent sv_filer:/vol/dest_vol/dest_qtree
rsh filer snapvault snap create dest_vol sv-hourly
(the snapvault snap create will wait until transfer is completed)
that way you don't have to install the SDK