Volo's Guide to Mosters is great expecially in its first part, where it gives various details and alternatives for some iconic monsters of D&D game..
It gives for example some alternative covens for hags.
There you can find other two covens I've developed for my games.
Conjuration. These hags master the art of calling beasts, plants, objects and extraplanar creatures for aid.
1st level: arms of Hadar, entangle, find familiar, unseen servant
2nd level: dust devil, find steed, web
3rd level: conjure animals, hunger of Hadar, spirit guardians
4th level: conjure minor elementals, conjure woodland beings, Evard's black tentacles, grasping vine
5th level: conjure elemental, insect plague
6th level: wall of thorns
Mind affecting. Some hags delight the power of mind control, either direct or through aimed Illusions.
1st level: charm person, change self, color spray, command, sleep
2nd level: crown of madness, enthrall, suggestion
3rd level: fear, hypnotic pattern, major image
4th level: confusion, greater invisibility, phantasmal killer
5th level: modify memory, dominate person, dream
6th level: mass suggestion