[KK]

Robert,

It would be difficult (if not outright impossible) to coordinate between a Couch managed template and a non-Couch managed script.

The best way, IMHO, is for you to go ahead and convert the list.php into a Couch managed template.

You are right, this will change its canonical URL but that does not mean you'll lose the existing PR - URLs of pages keep changing in due course of their life-times. That is why we have the '301 Moved Permanently' directive.
You can place it in your .htaccess file so that visitors accessing the older URL get redirected to new address and your PR simply gets transferred to the new page.

Hope this helps.

Thaks for your reply and I appreciate your patience
I will try to plan out like you said ..

I did the way u suggested .. everything working fine..
But when i add up 301 redirects to .htaccess file.. the pages are not displaying saying 'the webpage has too many redirects' I think because couch automatically redirecting lists.php to /lists/ by applying again redirect in .htaccess is causing the problem.. So i removed 301 redirects from .htacces file .. anyway I dont find any difference as per navigation n no errors.. and also tried to visit link through google results page.. no problem with redirection from there too.. hope the ranking doesn't fall
Thanks KK.. Couch Rocks!!

[KK]

I should have seen that
The change from '/lists.php' to '/lists/' is standard prettyURLs fare for Couch and it will handle it automatically by sending a 'HTTP 301 Moved Permanently' if the older URL is used to access the page.

Do, don't worry - the page's ranking will not suffer even one bit.