Osclass classified ads site modifications

1. Multiple child theme. I would like to create multiple child team from my Delta theme. There is a directive ([login to view URL]) to create a child team. Followed it and I was able to create a child theme. However I am only able to create just one. Need directive/script modifications to enable me to create multiple child themes. 2. External Link as a paid feature I have an osclass plugin called External Link(Embed users external links with server-side cloacking & redirect). The plugin ads a text field (website link) in the publish ad step. Where the seller can add a link to their website when placing item for sell in my site. I want to make this feature a paid feature, like the premium feature. I should be able to site the price for website link in the admin section. And the amount should show close to the website link text field. If a seller adds a link to the field, the amount should be added like when seller selects a premium option. The external link as a paid feature can also be done by replicating a current paid feature, such as highlight. but add the feature in the publish ads page as a text box. if the text box is filed the user placing the ads is charged. the content in the text box is added to the external link table in database. I can provide the external link plugin so you can see what would work best. Further questions, suggestion and comments are welcomed.