I’d do a deal to sell her products on consignment in your store. Agree on a cost price per item, set the retail price, and you only pay for the items that actually sell. You keep the difference.

She’ll take less profit, but if it works well, you can discuss carrying her products on a permanent basis instead of just the 2 weeks here and there that she currently does to you. By doing this, she can avoid having to man her stall, allowing her to either enjoy some free time or find another location to set up a shop, increasing her exposure. Selling on consignment also protects you from getting screwed over if she does open her stall in another location and tries to undercut your pricing since she only gets paid if you actually sell something.

I don’t see what’s wrong with being honest here.

“Sorry, but this is my livelihood. I can’t share proprietary knowledge”