NB: We want a proposed architecture for this, not necessarily the complete job although possibly pointers if you propose something outside the PHP/MySQL or general config options we don't know! We have a web-frontend in Magento using a multi-domain and multi-language scenario but we use WHMCS as backend, including using its Knowledgebase/Download area, Domainchecker & Cart. Since WHMCS is not truly multidomain, we use https with the main company-site, and then different system templates to get the same look and feel as the different main-sites with the ?systpl=changetemplate variable. Now, we'd like to have a better integration with the Search feature and make a concatenated sitemap so that each sitemap will contain the (magento)category/product/pages of the language and its domain, and that at least the main domain should also concatenate all the pages under WHMCS (particularly knowledgebase-pages). It needs to update itself (with cron or similar) as pages do change occassionally. For search, we can today decide to EITHER search the knowledgebase from the backend, OR the catalog in the frontend, but we'd like to get results from both parts end up. If it can't be solved in any other way than having the one form call two iframes within another page displaying "catalog-results" and "knowledgebase-results" next to one another, that may be OK if no alternative (XAV?) is possible. Naturally Google could be used, but we don't like that sponsored links for others may come up, and we'd like to keep the look and feel for our own page, but you may have a suggestion on how this could be doable?