I faced the same problem and found a solution. You don´t need to have a child. You can use association to. The trick is that the association must be in bouth cds. I want an association ZI_B in my view ZI_A: ..association [0..] to ZI_MLDB_B as... B and then you have to also in the view ZI_B: association [0..] to ZI_MLDB_A as A...

of course ZI_B must be exposed

Jarda