There were mothers using supplemental nursing systems (a fun tube system that allows mothers to give their child milk or extra milk if they have low or no production but still want their babies at the breast), and bottle - fed infants both with breast milk and formula. (theperfectpush.com)
The Medela Supplemental Nursing System works by filling a reservoir with the supplemental nutrition. (medela.com)
A lactation aid is also included in supplemental nursing systems (SNS), along with a disposable feeding tube device. (verywellfamily.com)