Anyone help with this one? OnCalc and search

I have a master-detail relationship between two tables.  The detail table
can have from 0 to about 5 records for each in the master.  What I want
to be able to do is search the master incrementally (I can do this fine),
but also to search over the whole detail database, leaving the records
visible in the master table which have detail records matching the search
criteria.  I am using Infopower 2 as well...

What I have tried is to have a calculated field which, for every master
record, concatenates all its detail records as one string.  Therefore I
only ever have to search the two fields in the master record, never
touching the detail record.  But, OnCalcRecord seems to work very
strangely!  When I move down using the slider it is always one record
behind in calculating the calc field (obviously from the way OnCalc works
it only look for a new record when something changes in the master).  
Secondly, the first set of master+calc. records shown all have the same
calc. field value.

So, if anyone can either a) help me with another way to do my searching
or b) help with why the oncalc is doing what I want, I would be very
grateful.  It seems something that would be fairly common so I'm feeling
it's just me missing something obvious :-(

Thanks
Robert McArthur