Normally, we consider Affiliates to be "independent sales reps" who are either selling your product directly, or referring sales leads to your site, in exchange for a commission; thus, our Affiliate programs are designed to operate with that framework in mind. See more info here on how our Affiliate programs work, with explanations of the different Affiliate link types:
http://www.e-junkie.com/ej/help.affiliates.htm
NOT RECOMMENDED - UNSUPPORTED HACK - USE ONLY AT YOUR OWN RISK!
If you are adapting our Affiliate program to reimburse your supplier for a product, or to split revenues for a product with someone but not others, this will only work with Affiliate Direct Links used as purchase buttons on your site.
This unsupported hack WILL NOT WORK with standard Add to Cart buttons nor Affiliate Hop Links, and you CANNOT have a regular Affiliate program at all if you are doing this; you can however use the non-JavaScript version of Add to Cart buttons for products which have no share percentage set, which will allow buyers to add other items to their cart. DO NOT set any common hop link URL or share percentage -- avoid using the Admin > Affiliate Program Settings screen at all, except to obtain the sign-up link URL you will use to join your partner to your affiliate program.
Also, you SHOULD NOT try to use this hack to calculate revenue sharing with multiple different suppliers, as the calculations can become inaccurate if a buyer tries to click a Direct Link for multiple suppliers' products. This is because all of the Direct Linked items would get added to the same cart together, but only the last-added item would set which "affiliate" earns commission for ALL items being ordered.
NOT RECOMMENDED - UNSUPPORTED HACK - USE ONLY AT YOUR OWN RISK!
First, you would need to use Seller Admin > Product-specific Affiliate Programs to set a share percentage and enable Direct Links ("affiliate links will link directly to E-junkie Cart") for your partner's product(s).
Then log out of E-junkie and register for your partner's E-junkie login on their behalf, stay logged-in as them, and visit your own Affiliate sign-up link URL to join their new account to your Affiliate program.
Then you would go into their Affiliate Admin and click Get Affiliate Codes, find your business and product to get codes for, and copy their Direct Link codes for the product(s) that should share revenue with that partner. Then you would paste their Direct Link code into your own site pages, where the link would function as an Add to Cart button (though the button image says Buy Now, you can change that image if you prefer). The supplier's own Direct Links should be the only way for anyone to purchase that supplier's products. Every time someone uses that button to purchase that product, the partner would earn whatever percentage you had configured for them.
Then after the end of each month, you would still need to go into Seller Admin > Pay Your Affiliates to generate the masspay.txt file that calculates commission earnings for the prior month, which you would normally provide to PayPal Mass Payments to pay out those commissions. However in this case, if you have only the one partner and no regular affiliates, you can just open this file to view their commission total for the month and pay them manually by PayPal or whatever means you wish.
RECOMMENDED ALTERNATIVE METHOD FOLLOWS:
If you simply wish to have your partner notified whenever his product sells, a simpler and more reliable way of doing that would use the Multiple Emails method of our Integration feature. In the settings of that product, enable "Send transaction data to a URL" and click Next until you reach the Payment Variable Information URL field, where you would enter this (where "user@example.com" should be replaced with your partner's email address):
http://www.e-junkie.com/ecom/oplug.php?&m_emails=user@example.com
If the product is already using http://www.e-junkie.com/ecom/oplug.php...etc. in that field for something else (such as PDF Stamping or Aweber integration), you can just add &m_emails=user@example.com at the end of that URL.
To calculate a revenue share, you can view your E-junkie Transaction Log for that product and the relevant time period, which will show you the number of orders and a revenue total for that product and timespan. Then just pay half that amount to your partner by whatever means you wish, or if you have a regular affiliate program, you could edit your monthly masspay.txt file to add a line for your partner before you upload the file to PayPal Mass Payment.