Is the follow-up about whether respondents will buy with Scheme 1 OR (exclusive, exhaustive) Scheme 2? I'll assume so for the answer below. My answer would change if the follow-up is the inclusive "or".
I take it the follow-up question isn't asked if the respondent opts for "none" in your CBC question, correct?
If my assumptions so far are correct, then you the follow-up question is the dependent variable for a second CBC model which you would model as a binary choice of Scheme 2 or Scheme 1 as a function of the attributes that described the alternative chosen in the CBC question. This is a data set you will need to customize in Excel and run in CBC/HB (I think it will make the most sense to run respondent-level utility models, as that will make your simulator make more sense).
This also calls for a custom Excel simulator, where you simulate two choices - first the choice among alternatives vs none and then a second choice that simulates the choice of Scheme 1 or 2 .
This might sound like a lot of work but it's pretty common that folks do something like this, because it's a pretty common structure for real choices in the marketplace.