Is it possible to populate a multi select (list) field with concatenated values retrieved from a 2nd form?

Fact pattern:

1. Form A (Master) includes fields for field number, lot, grower, crop (collectively referred to as a Planting).

2. Form B (Timecard) includes fields for field number and a multi select which I would like to populate with Planting.

Example:

1. Master includes records as follows:

    Field Number  Lot Grower  Crop         

    Ranch A 123   A    Taylor    Iceberg   

    Ranch A 123   B    Taylor   Iceberg   

    Ranch A 123   C    Fresh   Romaine

    Ranch A 124   A    Taylor    Iceberg   

2. On Timecard form, user chooses Ranch A 123 for the location worked.

    Wanting the Timecard Planting multi select to show the following options:

    Taylor/Iceberg <only 1 item desired despite the existence of 2 lots>

    Fresh/Romaine

Is it possible to achieve my objective?