Select box 4 Tables

Hello and sry for my english.

I have no idea what can i do with my problem. I hope everybody can help me.

I have 4 Tables.

Table A a_id

Table B b_id a_id c_id

Table C c_id d_id

Table D d_id

whit the table-association A 1--n B n--1 C n--1 D

In my View i have a for the association A-B-C.

The Problem is that i have in the selectbox double-data and i need one more selectbox for the association C--D in the same View. Like this I have search for the answer but i can find a solution for my problem.

Thank you very very very much.