I would steer away from getting involved in advertising for a parents business. However, you could find another avenue to help the parent promote their company.
For instance, in an effort to keep attendance up at our meetings, we have everyone put their name badge in a bag and we have a drawing for a door prize at the end of our meeting. The parents that are looking to promote their service/product can donate an item or certificate for your door prize.
We also solicit donations from these same people for our silent auction during our Halloween Carnival. They obviously receive recognition through the display of their donation, but we list their name in several publications leading up to the carnival. We also list them in a newspaper ad we publish after the carnival thanking all of the vendors/donors, etc.
I would think this would be a touchy issue. I don't doubt too that, some of them sell with the same company.
The only exception to this I would allow would be if they wanted to partake in a fundraiser type thing. After a meeting perhaps they could all, at the same time, offer their wares, with a percentage of the sales, if not all of the profit going to your group. It would be a win win thing then and no one would feel slighted. They may gain new customers out of it.
I have seen this used as a one day fundraiser but they invite many of these type of businesses in great variety to participate and advertise it through the school as a fundraiser and usually hold it on a Saturday. Each donate one of their items for a raffle.
Just my take on it.
We have parents who "own their own businesses" and would like to display their items at our meetings with the hopes of getting more customers. (For example, gourmet foods, makeup, candles, etc.) Our school does not have a policy about this and it is up to the board to decided whether or not to let the parents do this. Any suggestions?