How do you sell a group of sites/domains in a single transaction on sedo?

I assume you can describe the group of sites in the description for each single domain listing, but how do you handle the transaction when someone bids on a single domain but says they are interested in the group of sites in the buyer/seller sedo messaging system? Will there be any problems with Sedo if the buyer or seller stipulates that a group of sites are being negotiated for during the sale/escrow process? Also, if the buyer and seller agree that the sale price is for the portfolio of sites, the seller would not be able to push the single site to auction since none of the other bidders on Sedo would know the auction is for a group of sites, correct?