Offer Price Chart

Is there a way for the price chart to display all offers including those in the offers tab by vendors that create a product under the same SKU? Right now my chart shows only price history from offers submitted through the form so on the price feed i have offers from vendors that created a product under the same SKU but different price and offers submitted through the submit and offer form. I am wondering if there is an option to do this or possibly customize the charting plugin.