For the next update, I'll try to have some cross mod support with other modded sentry weapons. However most of them will be limited to just one sentry summoned at a time since they are coded that way. I can't change that from my end. The mod authors themselves would have to make the change, but I'm not sure if asking them would work since I'm basically a nobody right now. I'm also looking into the multiplayer issue. Perhaps some code is being handled differently between single and multiplayer. I asked around on the Discord channel. My current best guess is that the Shoot method is handled client side only. All the sentry weapons use this method to actually summon the projectile. However, the problem doesn't seem to be creating the projectile, but the fact that it randomly disappears which I have no idea why that would happen. I'm sorry that it isn't the solution just yet, but hopefully this is on the right track.
I ran out of time to reply to this earlier. Hmm... the part with The Twins sentry shooting cursed fireballs might be a bit debatable if I include that. I say that because I already have a Cursed Flames Turret and I don't want to outclass that so soon. I could make the behavior of The Twins cursed fireballs either have no gravity or act flamethrower like. The summon weapon related to The Twins either rams or shoots lasers. I'm also thinking of how I want to handle the turrets. Maybe one turret that alternates firing different projectiles like the Terra Turret does or two turrets side by side.
From a technical standpoint, there is no turret slots like that is minion slots. As in all turrets count as one toward the turret limit, where minions can have a variable count toward the minion limit, like the Optic Staff summoning two minions at once which each take up half a minion slot. Some mods have minions that take up two slots at once. If I were to summon two turrets for the price of one, I would have to make an invisible dummy sentry that's linked in such a way that when it gets removed, so does its turrets. It's similar to how I have the Water Tornado's sentry work.
Technical stuff aside, the other two ideas can work. It might be a bit tricky for me to code the probes, but otherwise it's probably the most related to The Destroyer.
It would basically be a weaker Staff of the Frost Hydra, but it could work. I haven't asked for a suggestion related to Forbidden Fragments because I would like to create the tornado effect from the armor and Sand Elemental as a sentry. Only problem is me trying to figure out the code to do so. It's not quite as simple as copy and pasting.
