Yeah, I’m not sure if we’re talking about the same thing. What I’m looking for:

I make a Mastodon account

I make a Bluesky account

I connect them via the bridge

I post on one account, the same content is posted on both accounts

If someone replies to my post on Mastodon (which all Mastodon users can see), I can reply using my Mastodon account

If someone replies to my post on Bluesky (which all Bluesky users can see even if they have not opted into using the bridge), I can reply using my Bluesky account

From what you’re describing, it doesn’t sound like the bridge can facilitate this.