I think that it can be done if the terms of the 'main' host don't say anything against it. Although there is a moral issue! But I think that you can pass over it if you're convinced that you, as reseller, provide better support than the 'main' host. This way , the dollars over the 'normal' price could be justified .
Think a couple hosts that offer reselling are allowing resellers to sell reseller accounts, and did this by manually requesting an account with the persons particulars and still billing the reseller, and leaving support issues up to them.