After going through all the add ons and trying MS products and family product etc,I found that Linked Products is what I was looking for.
BUT getting some problems in functionality. I can not figure out how to add product typs so I can have one main product and few selectable optional product for main product.
Screenshots are different then actual fields in admin area.(in product types page). so I am trying all combinations but no luck yet.
It looks like Zappo is not intrested anymore.I hope someone else can show me how to get main product with selectable optional products.
Thanks in advance.