This can be a followup to a different question I requested earlier (Earlier redirect question). My root .htaccess has several rules within this format:

RewriteCond %{REQUEST_URI} ^/leadership/detail/$
RewriteCond %{QUERY_STRING} q=([0-9]+)$ 
RewriteRule ^(.*)$ /$1?p=%1 [L,R=301]

However when I attempted to include this:

RewriteCond %{REQUEST_URI} ^/blog/detail/$
RewriteCond %{QUERY_STRING} q=([0-9]+)$ 
RewriteRule ^(.*)$ /$1?p=%1 [L,R=301]

It did not work. /blog/ is really a Wordpress install and I am thinking in it's conflicting using the .htaccess file that's in /blog/ which has the next:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress

How can i place (or edit) code snippet #2 within the /blog/.htaccess file to really make it work correctly?

Have your combined .htaccess such as this:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On

RewriteCond %{REQUEST_URI} ^/blog/detail/$
RewriteCond %{QUERY_STRING} q=([0-9]+)$ [NC]
RewriteRule ^(.*)$ /blog/$1?p=%1 [L,R=301]

RewriteBase /blog/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{QUERY_STRING} !^p= [NC]
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress