Highligth grid first row

I need to highlight the first row of a group of data lines, as shown in the attached images, when the cursor is within the group identified by IDCampione: 5002000410.

If I move to the next sample, the row related to sample 5002000404 should be highlighted, as shown in the other image. How can I achieve this using a TwwDBGrid?

first image

Second image