Redirection of htaccess Only on Main Domain Not on Addon Domain

Hi! I googled a lot but couldn't find solution to my problem. My problem is I have many redirections on my primary domain. Like say for http to https, to remove page extension. for error document. to remove trailing slash etc... But now I have a addon domain and all the redirection is working on that aswell. Plus my addon domain is ending with a url like maindomain.com/addondomain.com That's what am getting if I place any htaccess redirection on my primary domain. I want to remove my addon domain from my redirection. I tried many rules but most of the time result is same or am getting 403 error page. Please help me to resolve this issue. Thanks