Child theme not working


I have tried to read all threads so I am sorry if I duplicate.

I am using Buddypress Corporate theme. I followed the video and can change the footer.php with no problem. I have buddypress installed on the main blog and to keep design consistency I want to use the same theme on the subdomain blog for I need the same navigation on both blogs.

I need to

a. Add links to external sites in the navigation of both sites

b. When I activate the child theme on the main blog I get links under ‘community’ to the groups etc on the main site which is correct. However the links in the subdomain all point to non-existent pages on my subdomain ie I don’t have groups etc on my subdomains but the navigation menu looks for them.

I’ve been trying for ages to change includes/main-navigation.php in the child theme, I created an /includes/ folder the made the changes in the navigation to hard code links to my main blogs community sections but the changes are not showing in my child theme. I can change the footer.php though so I know I have got the right principal.

Please could someone point me in the right direction. Thanks.