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Well, it is difficult

The fold extending from the bend in vein M is present and strong in (virtually ?) all Sarcophagidae, Miltogramminae included.
It is uncommon in Tachinidae.
However, it does occur there, for instance in the tribe Exoristini and in several other genera like Linnaemyia, Zeuxia to name some.

So:
No fold -> no Sarcophagidae
Fold -> Sarcophagidae or one of those 10 % of Tachinidae

Life is not simple

Theo