@april-dunsworth
You ask about consignment in the title, but not in the detail, QB is unsuited for a consignment store, if that is what you are thinking.
As far as the vendor mall, it depends on your organization. Is each vendor space is run by the vendor on a daily basis, or do they just have a space, put stuff in it, and all sales go through one check out register?
You can create an invoice for rent and schedule it, but that is static, it can not deal with if this amount of sale reduce rent by ...