[Delmo Walters Jr.]

yes, i remember it too
i don't know the title, but the girl was the strongwoman of a little circus company: her father is a sort o Houdinì, and her two brothers is an acrobat and a knife-launcher.
some very good feats of strength: she brokes a chain to free a boy, she curls a gig to repair the wheel, and above all she snaps two straps flexing a double bic!!!! *_____*

Was this the Filmation Zorro cartoon, or the syndicated one that aired relatively recently?