how come on this position it’s a butterfly the Delta is like -7.14 when it can only go from one to minus one ?
The initial delta is on the ten lot, not per contract. Flies are bimodal to delta from wing to wing. The delta can approach (but not touch) 1K deltas. I see that you stretched the OTM to reduce the debit. Gotta be careful there. Your initial short D will become long D very quickly.