I have a grid with rows that represent hundreds of detail items,
related to various master records.
When I double click on a row, an editing form opens in which I want to
show the detail row's fields and also the master row's fields.

I also want to be able to use this form to add, edit & delete both the
detail items and master items.

What would be the best way to do this?

When I click on the detail row I could I suppose get the detail ID &
master ID and then open a standard master-detail form. But the detail
is the focus of this form and there is a large amount of data and I
want to show only one detail record at a time.

Perhaps the other way is to make a joined query (this is what I am
currently trying). But how can I make both the detail & master fields
editable in this case?

Many thanks for your assistance.

Mitch