Is it possible to filter lookup fields to limit the data to that which pertains to a record within the field. For example:

I have names of personnel who work on projects and the links go a bit like this

personnel table gives a unique personnel number, this then selects witha query a timesheet, which in turn opens timesheet details.

In the timesheet details, when the person is showing in the personnel table(either in table with subdata sheets or in a form), I want the projects they can look up (in the lookup field of timesheet details) only to be those projects on wich they are working. Any help would be much appreciated thanks.