It would help to know the specific relationships you've established between each table. You can use text to document the relationships in this format:
TableOccurrenceName-----<TableOccurrenceName (----< means "one to many")
TableOccurrenceName::FieldName = TableOccurrenceName::FieldName
You could also click Edit Post on your original message and upload a screen shot of this from your database.
It appears you have:
Staff::StaffID = Assignments::StaffID
But I don't know how you've linked in records from your Clients table here and we'd need to know that in order to suggest a solution to your issue. (knowing whether an assignment can be linked to multiple client records or only one client record is a very important detail here.)