From my knowledge, in datasheet view you can only insert a subdatasheet not a
form.  Since your form is based on a query or table I would just insert it
(the query or table) as a subdatasheet and edit the info from there.

The only other way around it would be to create a form based on the your
query that shows you the outstanding tasks and create a subform containing
the customer information (the query used to open the customer form) or add a
command button that opens the other form (the customer form). Hope this helps.