This question is something that the company you work for must answer. Usually you can read and review the Policies and Procedures for the Direct Selling company to get the answer to this question.
The following companies have been looked into by Personal Special and have been deemed as acceptiable to offer Customers a Personal Special or a Deal or Reward for purchasing from you, however it usually cannot be made public. So for example giving a customer a reward within Personal Special that only the customer is aware of, that is accepted. Making a comment in a group of some sort (for example on Facebook) that you gave someone a Personal Special Reward, and what it was is usually not accepted.
Color Street: "You may use social networking sites (Facebook, Instagram, Pinterest, Twitter, etc.) to promote Color Street products and the vision and to direct contacts to your personal website or external website. These sites may not be used to advertise sale of your inventory on hand or for advertising any personal specials."
As you can see you can use social sites to promote products however you cannot tell them about personal specials that you provide to customers. This is where PersonalSpecial.com comes in. Because you are not publicly stating what you are giving and who you are giving it to, there isn't a conflict of interest.
Scentsy: Found in the Scentsy Standards document "Personal specials, including discounts, giveaways, and other special considerations may be used as an incentive or reward for your Customers and Hosts. However, you may only advertise personal specials via one-to-one communications in person, email, direct or private message, telephone, or direct mail." Also "Social media: You may use social networking sites (Facebook, Instagram, Pinterest, Twitter, etc.) to promote Scentsy’s products and opportunity. These sites may not be used to advertise the sale of your Inventory on Hand or for advertising personal specials"
While it doesn't specifically state you're allowed to use an external source to offer personal specials, it does say you can, and the method to which you can offer personal specials are in person, direct or private message, over the phone or mail. Since customers will be able to earn the personal specials you offer and you are directly providing each customer with their own unique personal special, this should be in compliance with their rules.
Origami Owl: "Independent Designers may not offer coupons, discounts or specials on any online, ecommerce, or social media site. Independent Designers are permitted to provide discounts on a one-on-one or private setting or message."
You cannot sell online or offer coupons or specials online however you are allowed to provide discounts to your customers on a one-on-one basis, this is exactly what PersonalSpecial.com was designed for! Because you are not publicly stating what you are giving and who you are giving it to, there isn't a violation.