I consider the following an Enhancement request.

Presently, if one were to have two tables that were related, should the user 
try to delete one of the fields in either table that relate the two tables to 
each other, Base will not initially complain, but will throw an error upon 
trying to save the table.

Would it be possible to, instead of simply giving an error upon trying to save 
that the Field cannot be deleted, when the user initially tries to delete the 
field, ask the user if he/she is sure that they want to delete both the field 
tying that table to another and the relationship(s) with a Yes/No Dialog, and 
possibly if the user would also like to delete the related fields with a 
checkbox in the Dialog (by default unchecked)?

Steps to reproduce:
1. Create a database in Calc.
2. Create Table "Table 1" with Primary Key Field "Field 1A" and Field "Field 
1B".
3. Create Table "Table 2" with Primary Key Field "Field 2A" and Field "Field 
2B".
4. Open the Relationships Window.
5. Add both "Table 1" and "Table 2" to the Relationships Window.
6. Drag "Field 2A" onto "Field 1A".
7. Save and close the Relationships Window.
8. Open the Design of "Table 1".
9. Try to delete "Field 1A".
<Requested feature would go here>
10. Try to save the Design of "Table 1".
<Current implementation occurs here>

Thanks,
-Harrison N.