Is there an BeforeAddRow ?

I am working with OS Openspace.

I have a list of boundaries (Northings/Eastings) in one table and GPS data (Lat/Lng) in another.

I only want to add the grid data if the GPS data was in one of the boundaries (containsPoint(pos)).

or do you add the row, then delete the row ?

Unfortunately there is no such event in dhtmlxgrid.