...when the dataset is open?

I have a query that I want a couple of fields to be writeable by the
user. There are also fields that I need to change, but don't want the
user to change.

These fields all appear in a grid, so I need the ability to write to
the read-only fields from within my code, ie. temporarily make the
field non read-only, write the value, then make it read-only again.

The property IB_Query.FieldByName('READONLYFIELD').ReadOnly is Read-
Only (!), so I can't just switch it to false while I do the write.

Are there any easy ways around this? I know I can run a separate query
to update the field(s), but would rather find a more elegant way!

TIA,

Gary.