In chapter 9 verse 25 of the Bhagavad Gita, Krishna says this:
yānti dēvavratā dēvān pitṛnyānti pitṛvratāḥ |
bhūtāni yānti bhūtējyā yānti madyājinō.pi mām৷৷
Those who worship the demigods will take birth among the demigods; those who worship the ancestors go to the ancestors; those who worship ghosts and spirits will take birth among such beings; and those who worship Me will live with Me.
Here is what Adi Shankaracharya says in his Bhagavad Gita Bhashya:
Deva-vratah, votaries of the gods, those whose religious observances [Making offerings and presents, circumambulation, bowing down, etc.] and devotion are directed to the gods; yanti, reach, go to; devan, the gods. Pitr-vratah, the votaries of the manes, those who are occupied with such rites as obsequies etc., who are devoted to the manes; go pitrn, to the manes such as Agnisvatta and others. Bhutejyah, the Beings such as Vinayaka, the group of Sixteen (divine) Mothers, the Four Sisters, and others. And madyajinah, those who worship Me, those who are given to worshipping Me, the devotees of Visnu; reach mam, Me alone.
yānti gacchanti dēvavratāḥdēvēṣu vrataṅ niyamō bhaktiśca yēṣāṅ tē dēvavratāḥ dēvān yānti |
pitṛn agniṣvāttādīn yānti pitṛvratāḥ śrāddhādikriyāparāḥ pitṛbhaktāḥ |
bhūtānivināyakamātṛgaṇacaturbhaginyādīni yānti bhūtējyāḥ bhūtānāṅ pūjakāḥ |
yānti madyājinaḥ madyajanaśīlāḥ vaiṣṇavāḥ māmēva yānti |
I'm interested in the part in bold. Some of these figures are recognizable; you have Ganesha and you have the Matrikas, a group of goddesses worshiped by Shaktas. But my question is, who are the "Chatur Bhaginyadinis" or Four Sisters mentioned by Adi Shankaracharya?
Are they Shakta goddesses as well?