I have found this great framework and I so excited by using this! great job!

I need to solve the following problem :
[b]table_A[/b]:
id_table_a1
id_table_a2
info_a
....
PRIMARY KEY (id_table_a1, id_table_a2)
[b]table_B[/b]:
id_table_b
info_b
PRIMARY KEY (id_table_b )
[b]table_A_B[/b]:
id_table_a1
id_table_a2
id_table_b
PRIMARY KEY(id_table_a1, id_table_a2, id_table_b )
FOREIGN KEY (id_table_a1, id_table_a2) REFERENCES [b]table_A[/b](id_table_a1, id_table_a2)
FOREIGN KEY (id_table_b ) REFERENCES [b]table_B[/b](id_table_b )
I want to CRUD on [b]table_A[/b], and to CRUD on the relation n_n table (table_A_B ) selecting the values for field table_A_B with the info_b of TABLE_B....
I have try set_relation_n_n, but my problem is that table_A has a multifield key...
How do I solve this? :S
Thank you very much!!