Accounts with No products

[MoiraHeath]

Our users are trying to create a campaign based on accounts that do not have a particular product (of course, they can have more than one product on more than one opportunity). At the moment they cannot do it cause the system is catching any opportunities for any given account that has multiple opportunities with different products. Has anyone had this problem before? How did you work around it? The suggested solutions we were given are messy and involve a lot of manual duplication of data, which I am trying to avoid.

Any suggestions will be greatly appreciated.