This question is difficult, but let me try. I am going to change the link structure on my website and was hoping to have my index file basically handle most of what needs to be done in order of discovering what page needs to be opened (or included) based on the URL supplied. For now I'm leaving my original rewrites with updated canonicals to point search engines to the new pages. So, to keep rewrites, while allowing the index.php to pick up everything else, would this work?
RewriteRule ^/?trailer/([-0-9a-zA-Z#]+)/([-0-9a-zA-Z#]+)?/?([0-9a-zA-Z#]+)?$ file1.php?fkey=$1&tkey=$2&tres=$3
RewriteRule ^/?trailers/([0-9]+)$ file2.php?page=$1
RewriteRule ^/?communities social.php
RewriteRule ^/?user/([0-9]+)?/?([0-9a-zA-Z#]+)?/?([0-9]+)? usr.php?uid=$1&pagetype=$2&page_number=$3
//and so on and so on of rewrite rules... and then:
RewriteRule ^/?([0-9a-zA-Z#]+)?/?([0-9a-zA-Z#]+)?/?([0-9a-zA-Z#]+)?/?([0-9a-zA-Z#]+)? index.php?var1=$1&var2=$2&var3=$3&var4=$4
So basically if the URL doesn't fit any of the exact rewrites, then it checks it against the final rewrite url that has the index.php give it a look.
Would this work or create an immediate conflict?