Let me make sure I understand your question...
You have 3 tables:
Member Info
[tt]MName
Address
Phone, etc[/tt]
Video Info
[tt]VName
Video #, etc[/tt]
Rental Info
[tt]Phone
Video #
Rental Date[/tt]
You want to record the Return Date somewhere in your database.
Why not add that field to the Rental Info table? That way it is definitely linked to the rental date. When someone returns a video, you need to search the Rental Info table for the [tt]Video #[/tt] with the most recent [tt]Rental Date[/tt]. Put the return in that record.
If there is some reason you don't want to put it in that table, then you'll need to add a [tt]Rental ID[/tt] field to the Rental Info table. Then make a Rental Return table that has at least two fields, [tt]Rental ID[/tt] and [tt]Return Date[/tt].
Let me know if that doesn't answer your questions. Jonathan
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It is not fair to ask of others what you are unwilling to do yourself.
-Eleanor Roosevelt