I am asuming this Ideal Gift combination is a good deal even if you do not use the crab. I cannot fathom that you otherwise would be purchasing it.

If you are unable to have a substitution for whatever reason and you are concerned about wasting food, then why not just omit the offensive crab from the package when you order/purchase it at the store?

You still are getting the good deal on the rest of the items and at the same time are not buying something you will not use.

It is not the best solution, but at least you will not have to store then discard something you do not want.