Alright, I have two different htaccess files. One is hosted on website1.com and the other on website2.com.

I would like the htaccess from website1.com to use the code in both its file and the code from website2.com

For example, here would be what website1.com's htaccess would look like.

just some example code
more code
and more code here

<htaccess src="http://www.website2.com/.htaccess" />

Obviously <htaccess src="http://www.website2.com/.htaccess" /> is not real - but is there anything similar to it?

There is no method to allow this that I know of, however if both sites are hosted on the same server you can use a symbolic link (or shortcut) of one .htaccess file into another public_root directory. There may need to be some allowences set up in the Apache conf file to allow this to share across multiple domain accounts.

It may not be accepted by servers or hosters.

So, you'd like me to .htaccess your site
It's like you need to have a public htaccess.