2 of my friends had twins when their older babies were 18 months. One only BF her oldest for the first day, the other BF her DD for about 7 months.

The firsts twins were in hospital for 6 weeks, born at 32 weeks & she didn't try to BF them. They were in Sydney for a while (4 hours away) & she couldn't afford to stay there to keep up with feeds. She had her DS & her DP had to work. It was pretty tough til the girls went back to the local hospital.

The second changed her mind the minute she found out she'd have to feed them every 2 hours round the clock. She'd planned to up til then. But she had a useless DP who had no interest in helping her out. She was also in ICU with an infection for 10 days after their birth.

Even before I managed to be successful in BFing, I'd still have attempted it. Now I've successfully BFed 2 of my kids, I wouldn't think twice... I may have formula for desperate times, but I would plan to solely breastfeed.