we have already got a site with WP installed, which has got some customized codes i.e, URL's ending with .php or url having space..

now the problem is that we are installing BB Press which is creating problems or interfering with the customized URL,

so now we are planning for a additional WP mult-site installation on subdirectories, eg: example.com/sampleone pl advise on

• SEO impacts
• plugin support
• or are there any other methods we should try
• eg : install separate WP for all the other regions