How to remove conflict in .htaccess?

Question

htaccess

Hello.
There is a site on which it was made that when opening any subdomain (sub.site.ru), content from the main domain (site.ru) was shown, and the subdomain itself (sub) was passed as a get parameter. There were no problems with this part, it was implemented like this:

# DirectoryIndex index.php
RewriteEngine On

RewriteCond %{HTTP_HOST} ^(www.)?([a-z0-9-]+)\.site\.ru$ [NC]
RewriteRule ^(.*)$ index.php?sub_dom=%2 [L]

Then I needed to close all subdomains from indexing. To do this, I created two different files robot1.txt and robot2.txt. And I did a substitution with them from the standard "robots.txt" depending on the presence of a subdomain. If there is a subdomain, robot2.txt was opened, in which there was a ban on indexing. Made it with this code:

RewriteBase /
RewriteCond  %{HTTP_HOST} ([a-z0-9-]+).site.ru$
Rewriterule ^robots.txt$ /robots2.txt [L]

RewriteCond  %{HTTP_HOST} site.ru$
Rewriterule ^robots.txt$ /robots1.txt [L]

Separately, everything works as it should, but if you use these rules together, then the second does not work. And instead of "robots.txt" the index page opens.
I suppose that we need to make an exception to the first rule, but for a couple of hours I can’t figure out how to do it.
PS In addition to these two parts of the code, there is nothing else in .htaccess.

Answer 1

Got it right after posting the question.

# DirectoryIndex index.php
RewriteEngine On

RewriteCond %{HTTP_HOST} ^(www.)?([a-z0-9-]+)\.faberlicproject\.com$ [NC]
RewriteRule ^(.*)[^robots.txt]$ index.php?sub_dom=%2 [L]

# RewriteBase /
RewriteCond  %{HTTP_HOST} ([a-z0-9-]+).faberlicproject.com$
Rewriterule ^robots.txt$ /robots2.txt [L]

RewriteCond  %{HTTP_HOST} faberlicproject.com$
Rewriterule ^robots.txt$ /robots1.txt [L]