I've the following situation. I've written a web directory script in PHP. The content of the website depends on the domain entered, so it's different for all domains.

Now I have multiple domains and want use this same script for all my domains. What's the best way to do this?

I've webhosting that accepts unlimited add-on domains and parked domains. I've thought of using add-on domains and copy the scripts in each add-on domain folder. But when I need to modify my scripts I'll have to copy all those files to all those add-on domain folders again. Not too good.

Another way which I am now using is to use parked domains. I copied all the php files to my main domain and setup my other domains as parked domains. Now I just have one copy of my scripts.

My question is whether this setup will cause any problems in search engine rankings?

And if someone has a better idea to do this, I'would be more than happy to know

Thanks in advance!