I am not sure what you mean? You can reply by just clicking reply, follow by just clicking follow. That's how I am replying to your post right now.
Do you mean if you're viewing an "original page" hosted by another server?
Graze is a closed source extension so it's harder to tell what it does.
I'd prefer FediAct which is open source and does the same thing, I did a post about it a while ago:
FediAct for Firefox
https://addons.mozilla.org/en-US/firefox/addon/fediact/
FediAct for Chrome
https://chrome.google.com/webstore/detail/fediact/lmpcajpkjcclkjbliapfjfolocffednm