Welcome to the forum!
Maybe adjust your level of "no poaching" rule? Maybe don't poach an active FS, but one where the AM is inactive? Recruiting is hard™ already. It's super hard to find players to fill your camp with that are just sitting around NOT in a fellowship. Most people that apply to join mine are in existing fellowship but looking to change. Most of the established players are in this category. They know you can switch after tourney and before new Spire, so most contact you while they are still in old FS. If you think asking someone in an existing fellowship is wrong, then you've lost this whole group of people looking to move. The ones that aren't in a FS are usually raw new players, but I don't think I'm taking them anymore with the new chap 5 changes since we are a Spire-centric FS. They really have a hard time adjusting to Spire now with it not unlocked until Chap 5. I'm finding the investment time/growth period not rewarding for the FS. You can warn them 1000x they need way more T1s and they tell you they're fine and not short on T1s. Well, yeah...you can get by with 2 factories doing nothing for 5 chapters, but now you suddenly you need like 8 to climb. I used to recruit raw new players all the time because if you mold them from the beginning, then they can Spire from chap 3 on. Now it takes them weeks to finally reach chap 5, only to cry they can't do the Spire and you have to boot them bc they're not the right fit. Waste of everyone's time.
If you don't have a Spire requirement, I would still recruit the new players. they grow to medium sized players pretty fast. They'll also stick around longer if they "grew up" with you. The forum isn't that effective for recruiting because most people are already in a FS and there aren't that many eyes on it unless they randomly direct eyes here from in-game notifications. It is effective however, if you make friends here. We refer players to each other all the time. Even if we're not playing in the same world, someone in your fellowship might have another city in the world your friend's playing in.