cross selling doubts about new developments

Hello to all

We have the materials joined so if we sell one material, you have to include in the same salers order two or more materials.

We are looking one solution with the cross selling but the problem is that the relationship has to have one parent material and one or more children materials. You should have to put the parent material in the sales order so the system gives you the children materials.

Ej:

Cross selling

Parent material: Table

Children materials: chair 1 and chair 2.

If I put table in the sales order, a popup windows appears reporting me that I can include chair 1 and chair 2 in the sales order but If I put chair 1, the popup window doesn´t appear. I would create the following cross selling relationship:

Parent material: chair 1

Children materials: chair 2 and table

and

Parent material: chair 2

Children materials: chair 1 and table

Our issue is that all the materials are parents, so it doesn´t matter what material you put in the sales order. The system would give you the rest of the parents materials. Is there any chance so I can put only one relationship and I can have the three relationships (wiht a user exits, bapis,...)

Thanks in advance.