You definitely don't want to depend on
SET RELATION TO .....

inside grids. I was once (this was with VFP30 and I haven't
tried it again with VFP50) on the phone with Microsoft
for 3-4 hours total about this feature of VFP30.

The second table in a grid doesn't always update properly
when using SET RELATION TO commands.

They suggested I use views instead. Which was terrible
since ODBC (the tables were free tables) had to be used.

Gene