Leader and follower accounts
The leader is the account you actually trade. Followers are the accounts that mirror it. You place orders on the leader exactly as you always have — your platform, your hotkeys, your stops. MirrorFill watches the leader's fills and keeps every follower's position in line. (Some tools call the leader a master account. Same idea.)
What "mirroring" means here
Followers track the leader's net position, delta-exact. After every leader fill, each follower has a target: leader net × its multiplier, or an exact quantity you set. MirrorFill orders only the difference between what the follower holds and that target.
That one rule is why the edge cases stay correct by construction:
- A duplicate fill event changes the leader's net by nothing, so followers order nothing.
- Partial fills move the net in steps; followers step with it.
- A reversal (long 2 → short 1) is just a new target; the follower trades the difference in one move.
You're long 2 ES and a follower runs a 2× multiplier: it holds 4. You sell 1; its target drops to 2, so it sells 2 — not "copy my sell order", but "match my new position".
Copy groups: the rules
Followers are organized into copy groups on the Copy Rules page. Each group is one leader account, one leader instrument, and its own roster of followers — and each group runs its own engine, independent of the others.
The constraints are deliberate, and the app enforces them:
- An account can lead only one group. One leader, one set of rules — no ambiguity about which group a fill belongs to.
- A leader cannot also be a follower. Circular copying is a feedback loop; we refuse to build one.
- One account copies a given instrument in only one group. Two groups both writing ES orders to the same follower would fight over its position.
Want to lead NQ from one account and ES from another? That's two groups. See copy groups and multiple leaders.
Rules key to the root, not the contract
Copy rules are keyed to the instrument root — ES, not ESU6. When the quarterly roll comes, you start trading the new contract month on the leader and the rules keep working. No reconfiguration. The app shows a roll warning and an "Old contract" badge on positions still in the outgoing month; details in contract rollover.
Quick answers
Can one account lead two groups?
No. An account leads at most one group. Use a second account if you want a second leader.
Can the same follower appear in more than one group?
Yes — as long as each group copies a different instrument. One account can follow ES in one group and NQ in another, but never the same instrument twice.
Do I have to update anything when the contract rolls?
No. Rules key to the root (ES), never a contract month. Trade the new month on the leader and the followers follow.