Optional Product Attributes

HI All,

Can we make some of the Product Attributes as Optional in case of ABO.

We have Many products where certain Attributes are required only during the first Selling and not required later.

As Siebel doesn't support optional attributes we add them within out upsert calls.

can we make them optional so that in new provide we will add and if in Asset if they are not there we ignore them and will not change the Action code to Modify in ABO by Adding them.

Thanks in advance for your reply.