You see how it came out, that your redirection web was not due to the installation of MODx!
pasting this code at the end of your file should be able to redirect all traffic correctly.
! assuming that the second web is in the directory asshadowscollapse.com !
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.asshadowscollapse\.com$
RewriteRule ^ http:// www.fletcherwebdesign.com/asshadowscollapse.com%{REQUEST_URI} [L,P]
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.asshadowscollapse\.com$
RewriteRule ^
http://www.fletcherwebdesign.com/asshadowscollapse.com%{REQUEST_URI} [L,P]
is also possible that the main root of the second web page, have a htaccess file, which may be related or not, with this problem and should consult with the hosting service provider.
In any case wanted to clarify something:
Apache directives contained within the file. htaccess have endless possibilities to customize your web traffic, this means that it can be easy and complicated at the same time make more rules are respected.
You can not paste into this file, prove any code and anywhere, just because the code is in the official documentation of MODx, none can know that another type of redirect, this making your web server, and before applying any changes, you should analyze whether its modifications can cause the crash of other services. And you can not take the blame, the installation of MODx, or an example of MODx documentation in the case reported fulfills perfectly the proposed work in the same example.
this is my opinion, it is accepted or not, is just a personal opinion.
Regards.