In your query, be careful not to include a primary key from the "one" side of
a one-to-many relationship. Instead include the corresponding foreign key
from the many side. This is one of the more common reasons that renders the
query "non-updateable", meaning you can't edit the recordset.
To test the query, execute it and try to change some data. If you can do
it, then you can use the query as a RecordSource for your form. Otherwise,
you'll have to alter the query to make it "updateable". Google
"non-updateable queries" for a more complete discussion of what reasons can
cause this problem.
Hope that helps.
Sprinks